My personal story is change the filter every DIC cycle oil every other DIC cycle, whatever synthetic is on sale. After 290,000 just staining in the valve cover. 2008 2.2L. I never had any oil related problems, just gasket and cooling problems.

QS old timey problem was the paraffin wax they used was different from the other guys.

 

I wouldn't put Quaker State in a lawn mower!!!

My dad had a 440 6 pack road runner, that he always used nothing but Quaker State, well It came time for a rebuild, and when he tore it all apart it was FULL of sludge everywhere. That was the last time we used it.

 

o boy, ive always used QS synthetic, even the dealership here has QS as the only synthetic option..not sure if its a marketing gimmick between them and gm

 

IIRC, pennzoil has same parafin in it also..

 

H'mmmm, both are Pennsylvania crude oil.
Wasn't Pennzoil brand created by QS to try to save the name? I may be mis-remembering.

 

Theres a connection there somehow, not sure which way.. But I think you may be right.