# Changing Oil types



## ace (Aug 8, 2002)

Have a question that maybe most of you would know.

I recently had and oil change done on my 91 Sentra.
I told the workshop to put in synthetic oil as the previous oil change in mineral oil resulted in my car having poor performance.

This prompted him to advise me against changing oils from mineral to synthetic or vice versa. Reason being:

1) Using mineral oil, means you have to change more frequent (every 5000 km) as opposed to 10000 km.
2) The seals maybe accustomed to the thicker mineral oils and if synthetic was used, it might just leak thru into the engine compartment.
3) There is some chemical reaction between the residual mineral and synthetic oils which might result in sludge buildup in the engine sump and this will cause chokage to the oil filter as well as engine compartment.

With all his above reasoning, he advised me to stick to one type of oil and not to chnage the type at all.

how much of truth is there to this practice ?
Now that I've done a mix, is an engine overhaul necessary to remove the sludge buildup ?


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## toolapcfan (Jul 10, 2002)

This is a good question that I've never had answered to my satisfaction. I ran full synthetic in my '93 XE and I run it in my wifes '97 Grand Am and I'll likely switch my '93 SE-R over at some point. Now I'm not a mechanic, but I change my oil and filter every 3K miles or 3 months which ever comes first. Regardless of the weather where I live or what type of oil I use. There are people that choose to only change the filter every 3K when they use synthetic, and then change the oil and filter every 6K or some such nonsense. To me this is stupid. I figured, synthetic costs me a whopping $52 a year more than Mineral. That's about $13 per oil change more than mineral. I'm not a big enough tightwad that I'm looking to recoup a whopping $13 every three months by changing less often. If you want to do your car good and spend the same amount of money as if you were using synthetic, change it more often than you already do. The next thing is that synthetic and mineral oils have the same ratings, 5W30 is 5W30 regardless if it's mineral or synthetic. Which says to me that leaks are going to be no less or more apparent if you switch oil types. Now the sludge/chemical reaction thing, I can't verify, but I've nevver noticed it in the cars that I've switched over to synthetic. In fact, I recycle my oil to the same place that people recycle their mineral oil, so I doubt there is much to worry about. I have always heard that once you go to synthetic you can't go back to mineral. I can't confirm or deny that statement. Again, no mechanic or scientist here, but if they sell synethtic/mineral oil blends, which they do, then I'd have to say that the sludge/chemical reaction argument is unfounded. I can only speak from experience and I like the way synethetic looks when I change my oil. Old and new pour the same. I can't say that about mineral. Synethic oil requires a much higher temperature to break it down, therefore, it has the potential to protect your engine better than mineral oil. And that's enough for me to use it and justify $13 more per oil change. So if you've switched from one to the other, I really wouldn't worry about it. If you're going to use mineral oil, use the cheapest stuff there is, because the higher priced stuff is either the same stuff (in fact, most times, bottled by the same people as the cheap stuff) or like Pennzoil, they add shit to it like parrafin wax, which builds up in your engine and causes it to run hotter, which in turn breaks the oil down faster and results in more wax buildup and you can see how that might compound. Anywho, that's my .93 cents worth.


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## Raul (Sep 12, 2002)

Mike: I doubt they add wax to the oil. Here's a copy of a post I lifted in ford-trucks.com; a site I frequent (super site if you own a Ford truck). Read on: 

A letter sent to Quacker State:

Through out the net, there are many recommendations AGAINST using
Pennzoil, and Quaker State motor oils in automobiles because they are
parafin based. These parafins cause sludge build-up in automobile
engines more so than motor oils with ash bases. Your response? 


Their response was: 

Thanks for your e-mail. 
First of all, every engine oil made today that is API SD, SE, SF, SG,
SH, SJ or SL rated is made from paraffinic base stocks. This holds true
for Pennzoil, Quaker State, Valvoline, Havoline, Mobil, 
Castrol, etc. 

As far as forming sludge deposits -- no API SJ or SL rated motor oil will
form deposits unless an underlying factor is present. Usually there are
only a few ways to form sludge, such as: 

Not changing oil & filter often enough for the type of service 
A coolant leak into the crankcase through a leaky 
head gasket or cracked block 
A malfunctioning or plugged up PCV valve or hose 

Paraffinic base oils refers to the type (i.e., structure and shape) of
the oil used. Paraffinic oils provide the best resistance to chemical
attack, change little in viscosity when the temperatures change, and
are the most resistant to form sludge and varnish. Other base oils, like
napthenics and aromatics, are not used in any high quality motor oils
made today. Please see below for a detailed explanation of paraffinic
base oils. 

Paraffin: It's Not What You Think 

One of the most misunderstood components of a finished lubricant
product, from a consumer's viewpoint, is the role of paraffins in a
paraffinic base stock. Base stock is the base lubricating fluid into
which performance additives are added to produce a finished lubricant
product. A base stock is usually extracted from petroleum crude or
selected synthetic material. Paraffin base stocks originate from
petroleum crude oils. 

What is a paraffin? 
A paraffin is a molecule composed of hydrogen and carbon
atoms(hydrocarbon) arranged in straight or branched carbon chains.
Paraffins have excellent oxidation stability properties. This means that
paraffinic base oils are the oils of choice for high temperature
applications because they have excellent resistance to the chemical
reaction between heat and air. 

Because paraffin base oils do contain wax, they usually have poor low
temperature properties compared to other types of base 
oils. This problem is easily solved by removing most if not all of the
straight chain paraffins by a dewaxing process followed by the
addition of special additives called pour point depressants that give
paraffin based lubricants excellent low temperature performance. 

There is a myth that paraffins cause sludge deposits. This is not the
case. The fact is, engine sludge is caused by partially burnt fuel,
water and other contaminants that find their way into the crankcase
during stop and go driving (this can appear as a white or tannish
colored emulsion in the cooler parts of the engine like valve covers, oil
filler tubes or underside of oil filler cap). 

In addition to high oxidation stability, natural high Viscosity Index (VI)
of paraffin base oils makes them very desirable for use in high quality
passenger car motor oils. All liquids have a tendency to become
thinner as more heat is applied them. An oil's viscosity index is its
ability to resist change in viscosity with respect to temperature. The
higher the VI of an oil, the lower is its tendency to change viscosity
(become thinner) as it heats up. This is very important when it comes
to proper lubrication of an engine. 

Often when a mechanic tears down an engine and sees the presence
of sludge deposits, he/she will automatically point to the oil and
paraffins as the root cause of the sludge problem. In doing so, the
mechanic may forget to review the service history of the vehicle. An
engine which has a sludge deposit problem is often a engine which
was driven in severe service conditions and who's owner neglected to
keep his/her vehicle properly maintained, such as by extending the oil
drain interval, a malfunctioning PCV system or plugged valve, or a
leaky head gasket which allows ethylene glycol to enter the
crankcase. Extending the oil drain interval beyond the manufacturer's
recommendations allows contaminants to accumulate. Eventually, this
build up of deposits will plug oil lines, galleys and 
screens. This, in turn, helps accelerate the wear of engine parts. 

In conclusion, paraffin base oils are not an engine's nemy. They 
are actually one of an engine's best friends. The enemy is extreme
driving conditions and/or neglect of proper maintenance, among other
things. Any myth that paraffin causes sludge is just that, a myth. 

Thanks again for your e-mail inquiry and have a good weekend. 

Sincerely, 

Grant Weidler 
Pennzoil-Quaker State Company 
Lubricants Technology 
Technical Services Representative 
(800) 458-4998


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## toolapcfan (Jul 10, 2002)

Awesome post Raul, thanks! Actually my name is Rob, Mike Patton is the lead singer of a band called Tomahawk. You might remember him from various bands including Mr. Bungle or Faith No More. My sig is a comment he made when his band opened for Tool at a concert. Anyway, thanks for posting that. My Grandpa was a mechanic and operated a shop for probably 30-40 years and I think he fell for this myth as well. Good to know. You still have to wonder though, if all manufacturers' "dewaxing" is taken to the same extent though. Anyway, good info to know. Thanks.  

EDIT: Took a quick peek and found some interesting info about synthetic motor oil at Mobil's website. Click on "Why Synthetics?" and read what they've got in the different catagories, especially "Myths about Synthetics" and "FAQs". Essentially it confirms what I already thought. You can mix full synthetic will mineral oil, change intervals should remain the same and although it doesn't discuss it directly, I'd assume that switching between oils is not a problem, since mixing them isn't. I however don't put all my eggs in one basket, so I'm going to check some more. Can't necessarily trust the manufacturers, they have conflicting interest. 

EDIT 2: Check these out about "Miracle Addititves":

http://www.ftc.gov/opa/1999/9909/prolong.htm

http://www.ftc.gov/opa/2001/02/zmax1.htm

http://www.ftc.gov/opa/1999/9904/motorup5.htm

http://www.ftc.gov/opa/1996/9607/slick.htm

http://www.ftc.gov/opa/1999/9905/duralub2.htm

Doesn't necessarily mean the stuff doesn't work, just that the results can't be guaranteed and that the company's advertising is misleading.


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## Raul (Sep 12, 2002)

Thanks for clarifying, Rob. Mr. Bungle; Faith No More? Wow, maybe my kids (22, 20, 18) know these groups; they're likely out of my time frame.

I don't use Pennzoil;, or Quaker State -- but not because of all the sludge and wax stories. Although, I may give their "high-mileage engine" oil a try one of these days. I understand that Castrol is now putting out a similar product. 

Take care ....... Rob!


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## Centurion (Sep 5, 2002)

Well of course you can mix syn with dino: they sell synthetic blend oils. As far as leakage from the seals or some such nonsense, I swtiched from dino to syn at 26,000 miles. It now has 140,000 miles and it leaks literally not one drop of oil nor does it burn one drop of oil.


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## DILLIGAF Racing (Sep 23, 2002)

Changing over to Synthetic at 26,000 is ok. Its when you have 126,000 that you should worry about chaning to synthetic. The problem is the seals I guess get used to the thicker oil, and I suppose synthetic is "thinner" and is more likely to seap through the seals in the motor at that point. Thats what mechanic told me. My SE-R runs on synthetic. I don't know when it was switched (3rd owner). My other car has run on synthetic since the first oil change.


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## ace (Aug 8, 2002)

glad to know that the 2 types of oils can be used interchangeably. This brings me to the next point of using engine additives.

Being the 6th owner of my sentra, I noticed the cam rods and surrounding casing having some burnt oil stains (like overheated oil in a frying pan). Is this an indication that my engine compartment and sump have sludge buildup.

Would using additives solve the problem or would it be better to leave it alone.

My car is 11 yrs old and 228,000 km on the OD, my mech advised me against using additives and removing the sludge, as it might damage the head gasket from the chemical composition. (blue smoke at the exhaust he would say)

The only way was to strip the engines and clean it out manually. Of course cost is the factor here.

So what should I do ?
Leave it alone, or add the engine additive or Change my mech ?


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## samo (Apr 30, 2002)

I changed to Mobil1 10W30 syn at about 100,000 miles - not a drop of oil has hit the garage floor.


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## SergioCR (Sep 18, 2002)

...my two cents here... i'm using mobil1 syntetic... i guess it was something like 15/40 or 15/50 grade.... when i first got my 93 sentra it came with a VERY scary oil in... so i used a solvent added and mixed with the old oil that claims to clean the engine, i run it at idle for 5 minutes then changed the oil and filter... filled it with Havoline 20/50, run it about 1000 miles then added engine cleaner again, changed oil filter and filled it with mobil... it works great and the oil begins to get "brown-clear" at about 2000 miles. 

About the miracle additives, what do you guys say about X1R ? i'm using it on my engine and seems to run smoother and quiet, and also has a logo that says something about NASA Hall of fame "Certified Space Technology" it should be ok i guess. Take a look.


www.x1r.com


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## Yosho (Aug 11, 2002)

Hmmm... I don't think there really is a concensus among the general online car enthusiast community (meaning all makes/models) about Syn. Some groups swear by it and other's are very negative about using Syn.

I know many Honda Si and Integra GS-R/Type-R owners who will never use Syn again. Just go do a search on honda-tech.com to see what I'm talking about. On the other hand, Nissan owners generally have good experience using Syn. I know I've used it for the last 50k in my '96 without any problems. I've chosen not to use it in my other 2 cars however (I'll point out why at the bottom of this post). 

There is this myth that Syn is better for everyone than Dino oil is. I disagree with this. Putting aside the oil consumption/starvation issues that some make/model owners have run into... I don't see a clear benifit for most people other than the ability to wait longer intervals between changing your oil. 

Many people point to the higher break down temperature of Syn over dino. Yes, it has a slightly higher break down point, but if your engine ever reached anywhere near the maximum temps of a quality dino or syn. you're engine would fail long before the oil would break down. 

Many people point to the amount of time it takes for a dino oil to start loosing it's viscosity vs. a syn oil. Again, if you're changing your oil regularly, this shouldn't be an issue... if you tend to slip to 4k-5k then there certainly is a benifit to running Syn.

Many people point to reduced wear of a syn. over a dino oil. While this may be true, there are certainly many examples of cars (including SE-Rs) reaching 300k+ miles with regular dino oil changes. To suggest that you'll only see these miles with syn is simply not true. Besides, how many owners actually keep their cars (with the same engine) to the 200k or 300k mile mark? Not many. There are many reasons why owners don't keep there cars that lenght of time... but most of those are non-engine related. I'd like to point out the prime mechanical reason people don't keep their cars that long is because other parts break and make the car cost prohibitive to maintain. To my knowledge what type of oil you've used doesn't matter and won't affect if your head gasket or your front crank seal go out. It certainly has nothing to do with wheel bearings/CV joints/bushings/ect.

Still many more people point to cost between the 2 types of oil being too small to matter. This may be true if you don't change your oil every 3k using Syn, but if like a lot of owners that use Syn (including myself) you change your Syn oil every 2500-3k then the cost is a LOT more expensive over the life of the vehicle. To use an example... if you change your oil every 2500 miles using a quality dino oil such as Castrol GTX... asuming you purchased it for $1.50 a qt. your cost would be: $449.60 for 200k miles of service. If you used a quality syn. oil such as Mobil 1 (like I use in my SE-R) and purchased it for $4.00 a qt. your cost would be $1200. A difference of $750.40. Certainly enough to buy a low milage JDM SR20 if at 200k you decided you wanted to replace your "old" engine. Now these were just ballpark numbers as I couldn't find any online places to give me an exact price but I tried to error on the side of Syn to prove my point. I don't think you can buy Mobil 1 for $4 or cheaper a qt unless you purchase it on sale or as part of one of the 5 qt jugs.

Dino (Castrol GTX) Oil
(3.75qts x $1.50 = $5.62 for every 2500 miles)
(2500 miles / 200,000 miles = 80 oil changes)
(80 oil changes x $5.62 = $449.6)

3.75 qts x $4.00 = $15 for every 2500 miles)
(2500 miles / 200,000 miles = 80 oil changes)
80 oil changes x $15 = $1200)

While I think the real world costs of using Mobil 1 would be even higher than using Castrol GTX (or other dino oil) I think you'll see my point that the cost of Syn seems small, but if you add it up and expect to use it for the life of your engine... the cost differences really add up. Remember, isn't this why you chose Syn in the first place? You feel it will keep your engine running longer? Well for the cost difference between the 2 types of oil, you could buy a JDM SR20. Something to think about isn't it? I'm not saying that Dino is better for everyone than Syn is, just that before you jump to using Syn you should ask yourself a few simple questions first.

- How long do I reasonably expect to keep this car with this engine? (Remember there are accidents/rust/theft and many other considerations that should shape this answer.)

- Am I able to change my oil often enough (2500-3k) or do I tend to slip and wait longer?

- Do I know the cost difference between the two types of oil over the expected length of my engine's life?

-


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## Centurion (Sep 5, 2002)

Excellent and thorough post, Yosho. Tell us about why syn shouldn't be used in Hondas?


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## toolapcfan (Jul 10, 2002)

> The problem is the seals I guess get used to the thicker oil, and I suppose synthetic is "thinner" and is more likely to seap through the seals in the motor at that point. Thats what mechanic told me.


That's a myth about Synthetic. Synethetic and Mineral oils of the same numbers have to have the same pour characteristics. Therefore, Syn. can't be "thinner" at any temperature than it's mineral equivalent, otherwise the sanctioning bodies that be would not allow it to have the same ratings. 



> I don't see a clear benifit for most people other than the ability to wait longer intervals between changing your oil.


That's another myth. Synthetic has to be changed just as often as mineral. The manufacturer recommended oil change intervals are what are supposed to be followed, regardless what type of oil is being used. 



> Many people point to the higher break down temperature of Syn over dino. Yes, it has a slightly higher break down point, but if your engine ever reached anywhere near the maximum temps of a quality dino or syn. you're engine would fail long before the oil would break down.


This is not entirely true. It's not like oil doesn't break down until a specified temperature. Oil breaks down at all temperatures, it just takes varied amounts of time, relative to the temperature. That being said, oil breaks down at different rates throughout the operating temperature range of the engine. 

Although the price argument Yosho makes is very convincing you have to remember that unless you're able to do an engine swap yourself, which most consumers are not, you have to figure in labor for an engine swap, and that quickly outweighs the cost of Synthetic. You can see how Yosho did his math but I can tell you from personal experience, that synthetic costs me $38.40 a year more than mineral, It'd take 10 years for that cost as much as a cheap JDM. If you'd like to know how I figured it, here it is; I change my oil every 3K or 3 Months, and 3 months always comes first, and my actual mileage is typically closer to 2500 than 3K. That equates to 4 oil changes a year. When I buy mineral based oil I buy the $.99 stuff. So it only costs me $16 a year for motor oil. I buy Mobil 1 synthetic at Wal-Mart for $17 for a 5 quart jug, which works out to $3.40 per quart. So it costs me $54.40 a year. The difference between the two being $38.40. Now, I plan to swap my engine out myself sometime within the next year or so, but I still plan to run synthetic in it. But hey, we've got to make decisions for ourselves.


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## Centurion (Sep 5, 2002)

Everybody is forgeting about the slight increase in power and mpg's of syn (all due to reduced friction). Before anybody goes crazy, I did say SLIGHT. I read it's 3% better mpg's. I don't know about HP's.


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## Yosho (Aug 11, 2002)

I'm not sure people are complaining that Syn is thiner so much as it has the ability to leak around seals where the same standard of dino oil will not. I've read accounts of this and talked with many owners that have had this problem within the Honda/Acura community. For example, one Type-R owner had oil consumption so bad using Syn that he literally had to put a fresh qt. in every time he stoped for gas. He didn't have this problem when he switched back to dino oil. This is just one example, but there are many more. Other people use it in their B-series motors without any problems. I'm not sure why this is such a big problem with some B-series motors.

I don't agree that manufactuer's recommended oil change intervals are automatically the best. I know that many compaines are switching to using Syn because they're now including free basic maintance as part of the sales pitch and have changed thier recommended oil changes to 8-15k depending on manufactuer. Supposedly, these changes are not being made by the engineers but rather by marketing and sales. Because more and more cars are being bought on lease, they have to compete in the increasingly competitive "cost of ownership" catagory. They'd rather have the benifit of longer oil change intervals now than have a product that will last 300k. Again, how many owners actually keep their cars this long?


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## Guest (Oct 12, 2002)

I generally agree with what Yosho has to say about this. Just wanted to point one thing out... 



> For example, one Type-R owner had oil consumption so bad using Syn that he literally had to put a fresh qt. in every time he stoped for gas. He didn't have this problem when he switched back to dino oil. This is just one example, but there are many more. Other people use it in their B-series motors without any problems. I'm not sure why this is such a big problem with some B-series motors.


We have 3 race cars at our shop... two 91-94 classic's and a '91 type R powered civic wagen. All three cars have castrol syntec 5w50 in then at all times. with regards to honda motors... espicially the B series motors... these powerplants have some of the tightest clearences in the automotive world! What most honda owners that relentlessly run their mouthes about things they don't understand neglect to tell you is that their motor that is burning oil is probably one of the following:

1) Swap motors that sit in junk yards overseas that are then swaped without any internal maintainence tend to have dried out valve stem seals and gummed up oil rings. I see examples of this everyday! And yes, syn oil will be consumed more quickly, but not because it is thinner.... the fluid properties of syn. are very different that dino oil.

2) High milage, high abuse motors. Need I say more?

3) Motors that were rebuilt by someone improperly. Back to the clearances issue... then you through low silicone content pistons(you know, the kind that are extremely slow to expand while the cylinders are expanding very rapidly) into the mix and you have the recipe for massive oil consumption!!!

Our Type R wagon suffers from no excessive oil consumption and it's abused on a weekly basis! 

One thing to keep in mind is this:

Motors are designed to burn a small amount of oil. Think about it for a second... the oil rings are there to control the _amount of oil left on the cylinder walls_ when the piston moves downward. I grew up on BMW's and still to this day consider them to be one of the best engine manufacturers in the world. They say that a car should consume about a quart... that's right.... a full quart.... of oil between regular changes. This is made in reference to a factory fill of Castrol syntec with the intervals set at about 6k miles.
If a quart of consumption is good for an ///M car... then it'll be fine for my GTi-R powered B13!!!!!!!!!!!!!!!!!1


Take this for what it's worth.... just my 2 cents!

nick


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## chris859 (Oct 20, 2005)

I have been running mobil1 synthetic in both of my 200sx's with no issues(on freshened jdm engines), and I swithched my cougar(5.0L v8) over to synthetic at 158k...it has 193k now and still no leaks or any sort of oil related issues - still runs strong, and it only uses about 1/2qt of oil every 3k miles. tell the guy at the oil change shop to stick it somewhere...because you can mix synthetic oils with standard oils! Nothing bad at all will result, even many of the large oil manufacturers say that this is a big myth. synthetic isn't any "thinner" than normal oil... 10w30, is 10w30...that is a standardized measurement for the viscosity(thickness).


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## insp09 (Jan 26, 2006)

Not sure about your mechanics reason #1. Today's motor oils do their job's for longer intervals, mineral and syn.

Reason #2 - If an older car has a minor leak(s), switching to syn will cause it to leak more. Switching to syn in a newer car won't hurt anything.

Reason #3 - The only things that can cause that are neglect, and fuel/coolant contamination. Going for too long an interval or running with the level too low.


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## Bror Jace (Apr 26, 2003)

_" ...because you can mix synthetic oils with standard oils! Nothing bad at all will result, even many of the large oil manufacturers say that this is a big myth."_

I changed between mineral oils and synthetics seasonally with no ill effects.

_"Synthetic isn't any "thinner" than normal oil ... 10w-30, is 10w30...that is a standardized measurement for the viscosity(thickness)."_

Mostly. Each weight has a 'range' associated with it. Mobil 1, for example, tends to be on the thin side in each weight.

My last Honda and current Nissan use no measurable amount of oil between changes ... even if I extend my interval out to 5,000 or more miles.


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