# Question about synthetic oil.



## 91 3sgte (Sep 19, 2003)

Hey guys, I just bought my g/f a 2000 GXE with 70k. So far, we both love the car (I can't wait to get my 98 200sx SE) and want to keep it in tip top shape. So... I was wondering, with this many miles on the clock... would it be a good idea to switch to synthetic? Or should I just stick with regular? Also, how many of you guys switched to synthetic with more than 70k?


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## Bror Jace (Apr 26, 2003)

*91 3sgte*, the problem of synthetic oils (mostly early versions of Mobil 1) causing leaks in cars with 50,000, 75,000 or even 100,000+ miles on them are pretty much a thing of the past. Switching at any point in an engine's life is not really a problem ... nor is switching back.

Still, the effectiveness of some synthetics is a but exaggerated. I've seen dozens of used oil analyses and some oils like Pennzoil and Chevron Supreme offer the same, if not better wear protection for modest drain intervals up to 4,500 miles.

Synthetics handle extreme temps better (more stable in the heat, flow better in the cold) and they flow better than mineral oils if left in your engine for 5,000+ miles.

Lastly, there are a lot of Group III "pseudo-synthetics" on the market which claim to be 100% synthetic but are in fact merely highly processed mineral oil. Good oil but at $4+ per quart, they are a rip-off.  Most mass-market oils other than Mobil 1 (Pennzoil, QS, Valvoline, Castrol, etc ...) are Group III pretenders. 

I like the high-mileage oils, specifically Pennzoil's. They are actually something of a synthetic blend with about 10-12% Group V ester in them to act as cleaners and seal conditioners. Great stuff at ~$2 per quart. These tend to be on the thick side of each given weight so you might want to wait until spring to switch. I've heard of them minimizing minor leaks ... but not in every case.


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## Silvspec86 (Apr 4, 2003)

i agree, high mileage engine needs high mileage oil. but if you are a car freak and know what you and your g/f's car needs and how to take care of it, then synthetic will do also, but not really worth the $. synthetics are more for your street racer and track junkies, and ppl like us with some mods on the car, who's engines take a pounding...so unless your g/f is gonna race it home everyday, synthetic isnt really gonna be much different than regular. if you really want to keep it in good shape, use high mileage oils and use Motor Flush every other oil change, it'll keep the engine clean and running smooth. pennzoil is good but my friend has a Celica with 250K on the Od and he uses Castrol high mileage, i dunno which is better, i'm just telling you what i know. oh and dun forget the fuel system cleaner, every 3,000 miles!


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## 91 3sgte (Sep 19, 2003)

Thanks for the replies guys. BROR JACE - you said that the higher mileage oils are "thicker" wouldn't this be bad since I live in michigan where it gets really cold outside? Also, I read that synthetics are more viscous than conventional oils and they're better in reducing friction. So, don't you think synthetics, regardless if one races or not, are more beneficial than conventional oils? Thanks in advance for the replies guys!!


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## Silvspec86 (Apr 4, 2003)

well, a thicker oil wont harm the engine, and its not that much thicker. it might restrict high end power but it wont harm the engine in anyway. if you think about it, high mileage oil costs about $2 a bottle and mobil 1 syn costs $4, so its basically a cash thing. Nissans can take a beating so using different types of oils for everyday driving isnt going to change much at this stage. i would recommend synthetic but keep in mind that it is pricey and you should Flush the Motor before adding Syn. i use Mobil 1 5w30 Newer car formula ( with 7,600 miles)....i think i saw a high mileage formula at the store, so you should check that out. My family used to live in Chicago and we had a '87 Sentra XE, and we used just regular plain Catrol GTX and it ran great year round. so, Good Luck keepin it in good shape.


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## Lazarus_023 (Jun 3, 2003)

91 3sgte said:


> *Hey guys, I just bought my g/f a 2000 GXE with 70k. So far, we both love the car (I can't wait to get my 98 200sx SE) and want to keep it in tip top shape. So... I was wondering, with this many miles on the clock... would it be a good idea to switch to synthetic? Or should I just stick with regular? Also, how many of you guys switched to synthetic with more than 70k? *


how long you plan on owning it?
forever? maybe you can justify synth...
less than, say, 130k miles? prolly ok with dino.

it's all about how much you care, man... 
-if you so desire, will you be able to find something better for cheep 3 years down the road? most likely. save the $$ for a new-car fund.
-if you want to keep this car forever, maybe the synth, but driving nice will help it more.


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## 91 3sgte (Sep 19, 2003)

Hmmmmm... i don't think we'll have the car forever... However, my g/f job requires a lot of driving. She's had the car for about 4 days and she already put over 450 miles on it! So, i guess I will switch over to synthetic. It's a great car and she (we) love it so I figure we should take care of it so it'll last her for at least 4-5 years or 200k+ miles.


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## Bror Jace (Apr 26, 2003)

Yeah, the high mileage version of Pennzoil (which i think is _very_ good stuff is rather thick for a northern winter. Their regular stuff would be a pretty good choice, though.

*SilvSpec86*, I really mistrust most motor flushes or any other form of aggressive cleaning of the inside of a motor. I've seen these additives lead to blown headgaskets. The only cleaners I'd use in a motor is Scheffer Neutra 131 or Auto-RX ... both ester based and fairly gentle. Most cleaning of a well-maintained engine is unnecessary, anyway.

Also guys, don't forget that all synthetics are NOT created equal. There is a vast disparity between Grouop III, PAO, Group V (polyol & dibasic), etc ... and that's just the base oil and not the additive packages which vary as well.


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## Lazarus_023 (Jun 3, 2003)

Bror Jace said:


> *Also guys, don't forget that all synthetics are NOT created equal. There is a vast disparity between Grouop III, PAO, Group V (polyol & dibasic), etc ... and that's just the base oil and not the additive packages which vary as well.  *


ROFL.


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## Silvspec86 (Apr 4, 2003)

well, i dont use motor flush, but i do use really good oil. i'm just saying that with a car of that mileage, before changing to Synthetic, he should get all that grime build up that was caused by the previous owner and get do a good scrub down before puting in more expensive Synthetic.


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## Bror Jace (Apr 26, 2003)

_"I'm just saying that with a car of that mileage, before changing to Synthetic, he should get all that grime build up that was caused by the previous owner and get do a good scrub down before puting in more expensive Synthetic."_

Yeah, I understand ... and that makes a certain amount of sense but sometimes dislodging a lot of built up goo all of a sudden can cause engine leaks and chunks of stuff (now free) can get caught in smaller oil passages and clog things up ... not to mention clogging up an oil pick-up screen. Any of those scenarios can cause serious and costly problems. 

If you have a dirty used motor, you could use slight doses of one of the fluids I already mentioned along with short (1,000-1,500 mile) oil drain intervals. Be sure to change the filter each time. Use a cheap one like a Walmart supertech ... or some other $2-3 filter while doing this.

Heck, even using just a diesel/fleet oil (mostly 15W40) can often clean things up a great deal without additives. 

Again, if the motor is filthy, consider a few short duration oil changes to get things cleaned up safely.


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