GM switching back to 10W30 in some engines...

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Jun 10, 2002
Cordelia, CA
At the Texas State Fair in Dallas this weekend, while checking out all the cool cars at the car show, I noticed that the 3.8L Buick V6 equipped cars (Buick V6 is used in all GM brands except Caddie) all had "Use 10W30" printed on their caps. The Chevy 3.1 V6 equipped (again...not just used in Chevys) cars still called for 5W30. The rest had a little book symbol with an i next to it indicating, "Check the manual" which I assume means that the manual recommends different grades based on temp or some other special recommendation. Buick V6 is one of those engines that has had problems with front main bearing wear. I wonder if that might be the reason. Any thoughts/comments?
Actually, the 3.8 has always recommended 10w30 over 5w30. My 1997 Grand Prix GTP said that 10w30 was the recommended viscosity (both in the manual and on the oil cap) and the new ones say the same thing. I've often wondered why GM never went to a 5w30 recommendation on that engine. Perhaps they did testing and found that the 5w30 wasn't protecting well enough? One thing is for sure, the 3.8 engines are workhorses, they take a lot of abuse and still last a long time.
Indeed, as long as I can remember the 3800-II recommended 10W-30 unless you lived in the north pole. I run it without a problem. I find it ironic the LT1 recommends 5W-30, it certainly doesn't look like an engine that would recommend or run well on such a weight. In any case, all I can figure is they recommend 10W-30 since its designed like the old SBC's in that its 100% cast iron block/heads wise and runs a nodular iron crank. I'm surprised they don't run them in the S-10s, they run a lot better and seem to pull much harder than the 4.3L [Smile] I just hope GM doesn't start specifying 5W-20 in the new Ecotec engines they're designing.
Agree, my 2000 Buick Regal GSE recommends 10W30 as well. However, I have had a large copper count (ppm) in the oil analysis. It has been decreasing but still high.
Spector see my post on the RP thread that is active. If your engine is a 3.8 older design the high copper is unusual. The new modular engines are the copper "kings".
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