# Oil



## blue goat (Aug 19, 2004)

Is everybody using synthetic oil. Anybody using the 0W-30 oil the manual says you can use instead?


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## LarryM (Aug 17, 2004)

I let the odometer get past 500, then took mine to the local Oil Masters and had them put synthetic, but the recommended 5-30. I believe that Corvettes with the same engine come from the factory with synthetic, so why not the GTO?

The trip to the Oil Masters was a real hoot. I've been to it with my other cars, so recognized the manager when he came out to greet me before I pulled in. He admired the car for a bit as we chatted, then as he directed me to a stall said "I usually try to keep the guys from congregating around a car... but I don't guess I'll be able to do that." I told him it was fine, and he was right. All six of them were huddled around as they worked on it. The two guys that actually worked on the car shook my hand and thanked me for "letting them work on it." Now how often does stuff like that happen in your life?


---Larry


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## Bill Reid (Aug 15, 2004)

5W-30... same motor as the C5... well until the 05 GTO comes out then it will have the same LS2 as the C6. ANYWAY, yes they are the same motor.

We use 10W-30 Mobil1 down here in the hot azz Southwest.

Either one of these will work well for you


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## Redline (Aug 10, 2004)

It is better that the factory didn't send it out with synthetic... it is safer with regular motor oil so the piston rings seal right... With Synthetic the rings have a chance of not sealing right


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## LarryM (Aug 17, 2004)

Huh? Why would that be? Before putting it in my GTO, I read up on synthetics. The synthetics are a different molecule geometry, and uniformity. I don't understand why that would change how parts seal. ? Please explain.

---Larry


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## rock421 (Aug 7, 2004)

I've heard some different opinions on this one, but I can see where the synthetic oil does a better job at reducing the friction needed to seat the rings. BUT, If the bore is round and has the proper finish, and the ring package is of the right material, tension, and has the prober ring land clearance, then it should take very little time for the rings to seat. If the factory feels confident enough to run Mobil1 in the Vette, then I can't see it being a problem with any LS engine. 
My feeling is that waiting a few thousand miles is probably a safe thing to do. Change the oil at 500 miles or so, then again at 2500-3000. At that point the change to synthetic should present no problems.
I think that the factory QC has greatly improved over the years, and the rings are probably seated before the car ever hits the transport, so this probably isn't even an issue. Better to be safe than to be a "huffer".


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## Groucho (Sep 11, 2004)

Just spoke to the Gearhead What Be In Charge at the stealership, and he recommended using the regular mineral-based oil for the first and second oil change (at 2000 & 5000 miles respectively), _then_ switching to synthetic.


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## GTO TOO (Sep 10, 2004)

I mean on offense so please accept what I am about to say in that light. Dealerships SELL cars. They may have specialized knowledge to particular problems. However, what is said by a dealers tech. with reagrd to engine durablity is opinion. The difference between opinion and facts; are opinions may or may not be correct. Facts are what they are and do not change. Forums run on opinions. 

That said engines are designed and tested by engineers, and results validated under very controlled (including worse case ) conditions. The Corvette comes with the same LS1 as the GTO. ( the vehicles are obviously built in different countries which may be the reason a synthetic is not installed at the factory in Aussie land. ) But the engines are the same. If synthetics were harmful to engine break-in or ring seating issues, it would not be poured down the hole of the Corvettes LS1. 

The synthetic oil/ring seating issue is " urban myth". That is not born out by fact. That does not stop some from holding the opinion to the contrary.
The only place where less friction is bad, is between the contact patch ( on those big black round things ) and the road. Contact between medal " things" inside the engine is BAD. 

((( the last little bit is for those that do not wish to wade through any technical issues. )))))


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## LarryM (Aug 17, 2004)

Thanks GTO Too! That is pretty much what I would expect.

I did try to read up on synthetics before I put it in, *every*thing seem to be positive about it - other than the price. But hey, I'll gladly spend a couple extra buck to give my little GTO the very best! I'm trying to convince the wife to let me put a heater in the garage for those chilly evenings  


---Larry


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## LarryM (Aug 17, 2004)

Groucho said:


> Just spoke to the Gearhead What Be In Charge at the stealership, and he recommended using the regular mineral-based oil for the first and second oil change (at 2000 & 5000 miles respectively), _then_ switching to synthetic.


Isn't synthetic the mineral-based one? Regular being petrolium based?


---Larry


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## blue goat (Aug 19, 2004)

Decades ago when piston rings were chrome and such they took awhile to seat. That is no longer the case with todays rings. They seat almost immediatley. The opinions to wait and let things "break in" is based on this old information.


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## Guest (Oct 8, 2004)

Use synthetic to avoid acids in the chamber. Regular oils has sulfur in it which oxidizes to sulfuric acid eventually. Acis pits your engine by corrosion.


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## leaftye (Oct 11, 2004)

LarryM said:


> Isn't synthetic the mineral-based one? Regular being petrolium based?
> 
> 
> ---Larry


Regular is petroleum and mineral based.....it's one and the same. Synthetics are chemically manufactured. Here's a couple quotes from this month's Racecar Engineering mag:



> ...oils perform three basic functions. They keep metal sufaces apart, they aid cooling and they retain debris (rather than allowing it to recirculate and cause damage). ... The largest proportion is base oil. To this are are added detergents and dispersants, a viscosity index improver, anti-oxidants and anti-wear agents, a friction modifier and other things such as pour point depressant, seal swell additive, anti-foaming agent and rust inhibitor.





> Base oils fall into two categories--mineral and synthetic...





> Mineral base oils are derived from a physical separtion process--they're distilled, while synthetic base oils are chemically derived.


adearmas, NO street oil should ever corrode the engine. Pure race oils don't have extra additives to prevent corrosion, but that's because race engines aren't used long enough to corrode. If any oil you use causes corrosion, it's time to switch oils.


Eugene


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