# motor oil



## quentin508 (Apr 12, 2005)

just heard about 20w-50 not educated much on oil, is it worth the few extra dollars or what is an ideal motor oil which is better than normal oil.


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## tony200 (Mar 23, 2005)

for our cars, the best oil out there is mobile 1 synthetic 10w-30
read this article. http://www.sentra.net/tech/garage/engine.php#Synthetic Oils and Lubricants


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## Omega3k1 (Jan 6, 2005)

i thought it was 5w-30... thats what i'm running in mine is Mobil 1 5w-30


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## Ninety-Nine SE-L (May 5, 2002)

If you're in a colder environment 5w-30 is what you want.
Warm environment or summers, 10w-30

15w-50 or such should be for racing and hot environments, it's too viscous for everyday startup and use.

Mobil 1 is the best brand, but it is def. more espensive. 1 bottle is about the price of 2.5 bottles of dinosaur poop.


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## Zac (Mar 10, 2004)

Mobil isn't bad...but it isn't the best either.


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## quentin508 (Apr 12, 2005)

NickZac said:


> Mobil isn't bad...but it isn't the best either.


what is the best motor oil in your opinion ?


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## znamya (Sep 21, 2004)

quentin508 said:


> what is the best motor oil in your opinion ?



I have a related question also, I read that DELO 15W40 is very very good for its price. BUT did anyone put in GA16 and observed mileage drop or hard starting of the car. I know that 15 is somewhat viscous but does it really matter for summer, I live in Atlanta and the least temperature we will see for 6 months will be 65F. About your question, the best is hard to comment on, because there are oil which you cannot buy from store but can only order online, some special oils for racing and so on, for a regular driver I think Mobil 1 is good enough


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## NotAnotherHonda (Aug 7, 2003)

quentin508 said:


> what is the best motor oil in your opinion ?


royal purple i think?


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## bahearn (Jul 15, 2002)

NotAnotherHonda said:


> royal purple i think?


You're nit-picking. Any pure synthetic is a large jump over dino-oil for stability. Brands just juggle additive packages to distinguish themselves from competitors. 

Stay away from 15W-50 unless you live in an equatorial region where it never gets cold and usually gets very hot. Road racers could make a case for that grade, too.


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## Ninety-Nine SE-L (May 5, 2002)

I gotta say Royal Purple is a bit much, it's supposedly the best but how many people have tried it? Prolly no one here, b/c you can't find it anywhere. Why would you bother to hunt it down and most likely pay more PLUS shipping? I can go to any store here and pick up Mobil 1 and I would expect it to be 99% as good as royal purple. Going back to my original statement Mobil 1 is the best you can buy WITHIN REASON. If you're inclined to buy something better than Mobil 1 than you have too much time and money on your hands. Until technology gives some other company the leading edge over Mobil 1 and it's available at my local Advance Autoparts, I'll stick with Mobil 1.

Once again, as I and bahearn have stated:
5w-30 if it's cold (lets say average day temp. is below 65*F)
10w-30 if it's warm (average day temp. is above 65*F)
15w-30 if it's hot (average day temp is over 100*F)
You may switch viscosities for the seasonal changes.

15w-30 is also good for prolonged racing (not drag), and maybe, MAYBE the turbo guys who have oil-cooled turbos.

Also, keep in mind, if you have some reason to actually go up to a 15w-50 motor oil, there are better options you should consider:
Oil coolers, oil filter relocation, oil pan spacers, or anything that will allow you to use more oil (more oil = cooler oil*).

* When I say more oil = cooler oil, don't go outside and add an extra quart to your engine b/c too much oil is bad. Always use factory recomended values. Oil coolers, remote filter relocation, turbos, and pan spacers allow the engine to safely hold more oil than stock because there's more places for the oil to go.


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## Bror Jace (Apr 26, 2003)

Why don't people use the search feature? This topic comes up often and there are plenty of good threads on it. Search using the word "synthetic" or some of the many common brands of oil: "Castrol," "Pennzoil," "Mobil" or "Chevron."  

Mobil 1 is fine ... now ... but a few years ago I think it was a poor choice because of a weak additive package. Just because they advertise the most, doesn't make them the best.

I use Schaeffer's synthetic blends. They have a great additive package and are more shear stable even than some synthetics ... especially Royal Purple. 

http://www.schaefferoil.com/

Um, why do people think Royal Purple is so good ... because of it's 'kewl' color? 

20W-50 is too thick for any modern engine unless you are running extreme engine temps ... and in that case you best be using a top quality synthetic like Red Line, Amsoil, etc .... Doesn't _everyone_ know this by now? I can't believe they still sell the stuff in the quantities that they do. It's mostly good for basket-case oil-burning vehicles right before they are headed for the scrapyard. 

*tony200*, the oil discussion in that site/article is pretty poor and is discussed in this thread:

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=4;t=000386

People who live in Atlanta Georgia will have no problem turning over a 15W-40 oil first thing in the morning. Look for the newest Delo400 which says "Low Wear Formula" as that one has a lot of moly in it. Maybe use a synthetic blend 1515W-40 like Schaeffer Supreme 7000 which has 20-25% PAO in it and pumps like a 10W-30. 

_"15w-30 is also good for prolonged racing ... "_

I have never seen 15W-30 oil. Are you talking about M1 15W-50? 

_"Any pure synthetic is a large jump over dino-oil for stability."_

Not really true. Mobil 1 starts out thin ... and Royal Purple thins from a 10W-30 down to a 10W-20 in only 1,500 miles before oxidation slowly begins to thicken it back up. UOAs show that it thins quickly like no other oil I've ever seen.

And only Mobil 1, Red Line, Amsoil and a few other specialty brands are real synthetics (PAO, ester, etc ...). Many such as Castrol, Pennzoil, Quaker State, Valvoline are highly refined (hydrocracked) Group III mineral oils merely calling themselves "synthetic." They are not much better than Group II+ oils like Chevron Supreme or Pennzoil ... but triple the cost.


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## Ninety-Nine SE-L (May 5, 2002)

typo on the 15w-30


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## Zac (Mar 10, 2004)

I've been using Amsoil because I buy it in bulk. Royal Purple is :thumbdwn: I plan to get a UOA after I get 10k on my next Amsoil change (the cam install may throw some metal in the current run), and then try Schaeffers and get a UOA after using that after a few runs. I used Chevron for a few hundred when I did my cam install. Chevron has a great dino blend and I had no problem, although I have no UOA to say much more about them on my engine.


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## Sethticlees (May 30, 2002)

Mobil 1 synthetic 0w-30


I also have proof that Mobil 1 synthetic works best in our cars.


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## tony200 (Mar 23, 2005)

mobile 1 synthetic....... :thumbup:


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## znamya (Sep 21, 2004)

Sethticlees said:


> Mobil 1 synthetic 0w-30
> 
> 
> I also have proof that Mobil 1 synthetic works best in our cars.



Can you share the Proof please?


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## Zac (Mar 10, 2004)

znamya said:


> Can you share the Proof please?


I'de like to see that too just out of curiousity.


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## Sethticlees (May 30, 2002)

znamya said:


> Can you share the Proof please?





NickZac said:


> I'de like to see that too just out of curiousity.



Sure! I thought you'd never ask... 

Durring the beginning of this year when I did my engine swap I saw something that changed my opinion of Mobile 1 synthetic forever...
I was so taken back by the results that I have sworn to use only Mobile 1 for the life of my engine and likely every engine there after.

Here is a photo of an SR20 engine w/100k plus miles. Dino oil was obviously used its entire life. Look at the discoloration and crud.


















Now, I spoke with the former owner of my new engine and he said he had been the original owner and has used Mobile 1 synthetic it's whole life... 75,000 + miles...

When I got the engine home the first thing I did what pull the valve cover and this is what I saw...
Pic 1 
Pic 2 


The entire head looks NEW. I couldn't believe the inside of an engine could look this clean especially after some 75,000 miles + usage.
So I asked my buddy what kind of oil he's been using and he told me nothing but Mobile 1 Synthetic for the life of the engine.

My response was, "Then I will use Mobile 1 Synthetic for the remaining life of that engine."


Sure, any synthetic motor oil could have given the exact same results but I don't have any proof on hand to show you that. I do however have rock solid proof that Mobile 1 Synthetic works excellent in our engines and so I offer this to you. 
You can make your own decision but the proven winner in my book, from now on, is Mobile 1 Synthetic. :thumbup:


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## scooterbob (Jun 16, 2004)

I'm going to have to agree with Sethticlees. I have seen the same results on my own cars too. Just don't have any cool pictures like those. 10W-30 Mobile1 for life!


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## Ninety-Nine SE-L (May 5, 2002)

I agree as well. Here's my engine with 50k. It's never seen dino oil:


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## Omega3k1 (Jan 6, 2005)

sheesh i wonder what mine looks like cause its probably been run on some cheapo wal-mart stuff most of its 120k mile life... It was a rental car so they probably skimped on it.

Also how would i go about cleaning all that up... just pull head and start cleaning it w/ engine degreaser?


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## tony200 (Mar 23, 2005)

wow,your engine looks so nice and pretty.


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## Zac (Mar 10, 2004)

Very clean engines guys, but how does that prove Mobil 1 is the best? Dino oil and synthetic oil vary in quality primary based on additives. Also, I can only imagine that filter choice has a lot to play in the role of how clean your engine will be.


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## Ninety-Nine SE-L (May 5, 2002)

actually, I have no idea, LOL. If it weren't so goddamn difficult, I'd love to open up my VQ30 and see what the heads look like. I've been running Quakerstate 10w-30 in there w/ Nissan filters.


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## DraftEm98 (Jun 29, 2004)

Omega3k1 said:


> sheesh i wonder what mine looks like cause its probably been run on some cheapo wal-mart stuff most of its 120k mile life... It was a rental car so they probably skimped on it.
> 
> Also how would i go about cleaning all that up... just pull head and start cleaning it w/ engine degreaser?


 Isnt it bad to switch to synthetic after you've been running regular for that long? Im at 133k and was told that the added cleaning detergents in synthetic would remove the oil deposits on my seals. Once an engine gets that old, it needs those deposits to help keep the seals from leaking. Kinda like picking a scab. It bleeds a little after you pick it. Anybody know the facts?


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## Omega3k1 (Jan 6, 2005)

well i've put 3k on the mobil 1 so far and the engine is still clean as a bell, no leaks, doesnt burn oil, man i love this car.


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## funkpacket (Feb 13, 2004)

its seems this thread has rid me of my habit of changing my oil every 2k with penzoil 10w30. When i replaced my valve cover i noticed it was a little discolored , probably in between the clean synth photo and the dirty as standard oil photo above. Would it be prudent to use an autorx type product and then switch to full synth? BTW, my ga has about 170k on it.


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## DraftEm98 (Jun 29, 2004)

funkpacket said:


> its seems this thread has rid me of my habit of changing my oil every 2k with penzoil 10w30. When i replaced my valve cover i noticed it was a little discolored , probably in between the clean synth photo and the dirty as standard oil photo above. Would it be prudent to use an autorx type product and then switch to full synth? BTW, my ga has about 170k on it.


 170k and still going strong, eh? Sweet. You might wanna go with a semi-synthetic to start with... maybe for two oil changes. Move up to full after that. Anybody else have any suggestions?


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## funkpacket (Feb 13, 2004)

DraftEm98 said:


> 170k and still going strong, eh? Sweet. You might wanna go with a semi-synthetic to start with... maybe for two oil changes. Move up to full after that. Anybody else have any suggestions?


Aside from a little hesitation between 2500 and 2700 rpm, my ga runs like its brand new. I cant say the same for the paint and the struts, but im planning to get at least 300k out of this thing


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## Bror Jace (Apr 26, 2003)

Guys, those pictures are great, no doubt, but that's far from 'proof' that Mobil 1 is 'the best.'

I've seen a Subaru flat-4 stripped down and it was just as clean. Car had 75,000 miles on it and it only saw Chevron Supreme every 3,000 miles.

My 8+ year old lawn tractor has had various brands of synthetic and dino oils but has been using Schaeffer 15W-40 synthetic blend for the last couple of years, Looking through the oil filler hole, it looks like the motor was assembled yesterday despite having 700+ hour of run time on it and only annual oil changes. 

Now, the current version of Mobil 1 is great for our cars, but proof that it's the best? I don't think so ... not quite.

Don't forget that cleanliness does not necessarily mean it has protected the best against wear. Too much detergency can compromise protection ... oils are a balance because they have to perform a number of tasks. I'm not saying that's likely ... but people doing constant engine flushes using solvent-based products will have a clean motor ... which may have thousands of miles taken off it due to premature wear.

Best way to tell an oil's quality through consistent UOA testing ... and even that can be difficult to discern. 

Also, dirty engines can be a sign of neglect, a sticking PCV valve, short trips without proper warm-up, etc ... Lots of variables in play, not just the quality of the oil.

Bottom line, current Mobil 1 is good stuff ... but there are many good routes available to the desired outcome of having a clean, well-protected motor. Some have nothing to do with the word "synthetic." 

PS - I'd take Walmart's SuperTech over some dinos like Valvoline All-Climate anyday.

PPS - And yes, you can switch to synthetic pretty much anytime. There's a _possibility_ you could have a leak (there's always a possibility, even staying with your old oil)


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## myoung (Apr 15, 2002)

NickZac said:


> Very clean engines guys, but how does that prove Mobil 1 is the best? Dino oil and synthetic oil vary in quality primary based on additives. Also, I can only imagine that filter choice has a lot to play in the role of how clean your engine will be.



Synthetics don't leave carbon deposits and sludge like dino oil, nor does it have contaminants left over from the refining process like sulfur (only to name one of many)... 

Those pictures tell a pretty good story.. if you don't want to believe it then nothing is going to convince you..


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## Zac (Mar 10, 2004)

myoung said:


> Synthetics don't leave carbon deposits and sludge like dino oil, nor does it have contaminants left over from the refining process like sulfur (only to name one of many)...
> 
> Those pictures tell a pretty good story.. if you don't want to believe it then nothing is going to convince you..


Ok...and that proves Mobil 1 is the best synthethic how? That was my original question their. I realize synthetic is generally better, but there are also many good dino oils as well. The pictures show clean engines, but one is with dino and one with synthetic...pictures tell a good story but not everything.


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## myoung (Apr 15, 2002)

NickZac said:


> Ok...and that proves Mobil 1 is the best synthethic how? That was my original question and I am posing it to you now.


Sorry I thought the Q was is Dino as good... my apologies.. :cheers: 

I agree with you from an earlier post.. Most synthetics are pretty much the same.. Mobil 1 is only cheaper because it's mass produced by one of the largest companys in the world.. others like Red Line, Royal Purple, Motul simply have to charge more because of production costs.. A dollar more a quart doesn't make it any better...just more expensive 

As you know they now have 50/50 synthetic/dino oil... I guess for people that can't make up their minds, or only want to spend a buck more than the WalMart oil.. 

I would have to look it up, but it seems to me that I remember Royal Purple actually being rebottled from another producer... (fragments of info bouncing around in my head...lol)


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## Zac (Mar 10, 2004)

myoung said:


> I agree with you from an earlier post.. Most synthetics are pretty much the same.. Mobil 1 is only cheaper because it's mass produced by one of the largest companys in the world.. others like Red Line, Royal Purple, Motul simply have to charge more because of production costs.. A dollar more a quart doesn't make it any better...just more expensive
> 
> As you know they now have 50/50 synthetic/dino oil... I guess for people that can't make up their minds, or only want to spend a buck more than the WalMart oil..
> 
> I would have to look it up, but it seems to me that I remember Royal Purple actually being rebottled from another producer... (fragments info bouncing around in my head...lol)


But Royal Purple and Redline have been shown to cause quite a lot of wear and do not seem to be good candidates for long drain intervals. From what I have seen, the cleaners in Redline may work a bit too well and cause excessive engine wear. That could equate to clean but worn internals. As far as Royal Purple, it seems to have quite a few sketchy parts to it, one being how quickly it wears and the other being the dye that disapears...


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## myoung (Apr 15, 2002)

NickZac said:


> But Royal Purple and Redline have been shown to cause quite a lot of wear and do not seem to be good candidates for long drain intervals. From what I have seen, the cleaners in Redline may work a bit too well and cause excessive engine wear. That could equate to clean but worn internals. As far as Royal Purple, it seems to have quite a few sketchy parts to it, one being how quickly it wears and the other being the dye that disapears...


been shown by whom...? 

"From what I have seen, the cleaners in Redline may work a bit too well and cause excessive engine wear".... Share what you've seen...proven by what test?


if you know all this and have done the research then why are you asking? Write it up... :::shrug:: I don't get the point of the question if you already have the answers.. Just in a argumentive mood?


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## Tavel (Aug 21, 2004)

i dont think the oil has a whole lot to do with an engines cleanliness. after reading this thread i took a peak into mine and my girlfriends valve covers (through the oil fill hole) and noticed that hers is substantially dirtier than mine...both have used 10w30 dino since the day they were bought(at least according to el maintnence records). i use 5w30 dino (supertech) in them now, and i'm going to replace the pcv valves in both someday soon...for the first time ever!


BTW: i have absolutly no idea how to change a pcv valve, any tips?


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## Zac (Mar 10, 2004)

myoung said:


> been shown by whom...?
> 
> "From what I have seen, the cleaners in Redline may work a bit too well and cause excessive engine wear".... Share what you've seen...proven by what test?
> 
> ...


I've been reading up on BITOG a bit. I'm still learning as I still ask questions and there are many variables in oil. If I knew everything, I wouldnt need to be on a forum, but I am glad I have this site to enrich my knowledge as well as BITOG. 

I have read that Mobil 1 will slowly get rid of sludge but it is not a high detergent oil and it will take time. My initial reason for the second post was that comparing a single synthetic (Mobil 1) to a single dino oil does not prove that Mobil 1 is the best, but I am not denying the advantages of synthetic over dino. When my cams went in, my engine was very clean and I have ran Amsoil for the last 30k miles. Maybe comparing the engine pics of Mobil, Redline, RP, Schaeffers, Amsoil and a few others will show what is better, but the UOA seems to tell what is wearing and what parts of an oil excels or fails.

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=001333 <--one of the many great UOAs that Schaeffers have yielded which is prompting me to shift from Amsoil.

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=000170 <--Schaeffers on a Nissan QG18, also looks good.

http://nissanforums.com/showthread.php?t=56098& <--Redline UOA on a Spec V which is lackluster, like many other UOAs on Redline; it seems to be a race oil and not one that I would want to put many miles on. Mind you, this test saw many cold starts, but this is where a synthetic should excel, not fail.

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=001946 <--another Redline; lead and iron levels always seems to be high on Redline oil.

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=002422#000000 <--Mobil 1 on a Spec V

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=001922#000000 <--The Chevron dino oils on Nissan engines seem to mix very well also as shown on the QG18.

My main point was that the pictures show Mobil 1 is better than dino, but it does not show that it is better than other synthetics.


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## myoung (Apr 15, 2002)

NickZac said:


> My main point was that the pictures show Mobil 1 is better than dino, but it does not show that it is better than other synthetics.


I agree 100%

Thanks for the links.. I have some good reading material now


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## bahearn (Jul 15, 2002)

Some people have reported that when they switch to synthetic they get leaks around some external seals. I made the switch at 22K miles and had no issues at all for the next 58k miles.


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## Bror Jace (Apr 26, 2003)

*myoung*: _"Synthetics don't leave carbon deposits and sludge like dino oil, nor does it have contaminants left over from the refining process like sulfur (only to name one of many)... "_

Actually, early PAOs (the base oil in Mobil 1, Amsoil and others - Group IV synthetic) had problems with cleanliness. They had _less_ natural detergency than mineral oil and this lead to a problem with their inability to keep airplane engines clean. Lead (from the aviation gasoline) would build up in the cylinders and (eventually) blow the motor. They rectified this by adding esters to the mix (Group V synthetic oils) which also helped with additive miscibility and seal conditioning.

Modern refining of mineral oils like Group II, II+ and III do not allow significant amounts of sulphur and other damaging contaminents to stay behind.

Mobil 1's ability to keep motors clean comes mostly from its additive package ... and those same compounds can be found in some mineral oils as well.

That's a problem with many people and their view of synthetics ... they usually don't distinguish between the base oil and the additive package. For short and modest drain intervals, I think the additive package is more important to keeping an engine clean and preventing wear.

A few years ago, when Mobil 1 had their SJ "Tri-Synthetic" version out, it had a great base oil but a very skimpy additive package and it was not uncommon to see UOAs showing a lot of wear. Fortunately, Mobil 1 has gotten much better since.

_"I agree with you from an earlier post.. Most synthetics are pretty much the same.. Mobil 1 is only cheaper because it's mass produced by one of the largest companys in the world.. others like Red Line, Royal Purple, Motul simply have to charge more because of production costs.. A dollar more a quart doesn't make it any better ... just more expensive."_

Completely untrue. Synthetics these days have never been more different. There are many types of PAOs, Esters, Group III base oils as well as alkylated aromatic compounds. All are synthetics 9depending how you define the term) and most of the different brands have very different formulations. Mobil 1 is cheaper mostly because Mobil is a much larger company than any other competeing brand. Simple economies of scale.

Red Line is the most expensive (generally) because their polyol ester base oils are _extremely expensive_. 

_"As you know they now have 50/50 synthetic/dino oil... I guess for people that can't make up their minds, or only want to spend a buck more than the WalMart oil..."_

Really? You know for a fact that the blends are a 50/50 mix?  Because I've seen lots of documentation on these over the years including MSDS and other factory spec sheets and I've never seen a blend with more than 25% synthetic ... and most brands are using a Group III synthetic which is merely super-refined (hydrocracked) mineral oil and not a 'true' synthetic like a PAO or ester. In short, these are a rip-off unless you know the synthetic component is real synthetic and is at least 20% of the base oil's volume.

_"I would have to look it up, but it seems to me that I remember Royal Purple actually being rebottled from another producer..._"

Nope. I'm pretty sure they are their own blender. They buy base oil stocks from refiners (say Mobil and others) then blend the final formula themselves. I think their plant is in Houston.

I maintain that problems with synthetics and seals are pretty rare these days. Don't forget that many "high-mileage" oils are actually synthetic blends ... using Group V esters to help condition the seals.


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## kahoots (Aug 25, 2003)

is it true that once you go to synthetic you cant go back to normal motor oil?


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## Zac (Mar 10, 2004)

kahoots said:


> is it true that once you go to synthetic you cant go back to normal motor oil?


that is false. you can switch to and back whenever you want.


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## kahoots (Aug 25, 2003)

any1 try castrol gtx 75000+ mile oil? I just did my oil change with it. I used 5w-30 and i live in nyc now, avg temp during summer is 80-95. Is that okay or should i change it to 10w-30 since im in a higher temperature range? Autozone said i should use 5w-30 since it said that in the computer but you know how autozone is always wrong. Thanks in advance


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## znamya (Sep 21, 2004)

kahoots said:


> any1 try castrol gtx 75000+ mile oil? I just did my oil change with it. I used 5w-30 and i live in nyc now, avg temp during summer is 80-95. Is that okay or should i change it to 10w-30 since im in a higher temperature range? Autozone said i should use 5w-30 since it said that in the computer but you know how autozone is always wrong. Thanks in advance


In my opinion, you are perfectly fine. It does not worth lose that nice oil. But next time, I would use 10w30.


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## Tavel (Aug 21, 2004)

kahoots said:


> any1 try castrol gtx 75000+ mile oil? I just did my oil change with it. I used 5w-30 and i live in nyc now, avg temp during summer is 80-95. Is that okay or should i change it to 10w-30 since im in a higher temperature range? Autozone said i should use 5w-30 since it said that in the computer but you know how autozone is always wrong. Thanks in advance


autozone is actually right on this one. 5w30 can be used through the whole temperature range, whereas 10w30 can only be used from like 32F to 100F or something like that. (just look in the owners manual)

there is no reason to switch to 10w30. it's thicker on start so it still causes excess wear on startup, using 5w30 will prevent this excess wear by being half as thick when cold, which lets it flow easier

10w30 and 5w30 are the same thickness when warm, the only difference is when cold.


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## Bror Jace (Apr 26, 2003)

_"10w30 and 5w30 are the same thickness when warm, the only difference is when cold."_

It used to be that 10W-30 was more shear stable than 5W-30 because the narrower spread betwen the numbers meant less unstable VII (viscosity index improver) needs to be used to bridge the gap between the numbers. 

However, in the last several years, some VII has gotten better (more stable) and the latest oils seemed _designed_ to shear some in order to produce less hydrodynamic drag inside the engine and improve fuel economy by minute amounts.

So I don't know if that generalization is still true. 

I still prefer a 10W-30 for the warmer weather ... but wonder if there really is a difference in shear stability anymore.


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