LLC5
Well-known member
You know, things have changed. 10W/40 used to be a common and pretty popular option back in the day for an oil with every day utility. Since then, I've had cars that specifically advise against using 10/40, and I haven't seen a manufacturer recommend it for a lot of years. I guess we can rack that up to improved viscosity enhancers in the lighter weight oils that make moving up to 40 weight unnecessary. That's all probably a good thing.
That would be CAFE.
	
I would be willing to bet that the problem is with  "the blue GM Oil filter".
	
	





