Maybe... I wonder about the blind faith put into the SM rating. For example, Superflo and Castrol GTX are stated on the bottle as meeting GM 6094, yet many do not state the spec, and even digging into websites does not reveal a compliance. Havoline does not list the spec on the bottle, but does on their website for example. It is my understanding that to follow the OLM from GM, that the oil must meet the spec. I couldn't find where QS (or Pennz, or Shell; basically any of the SOPUS offerings in conventional). That being said, I still bought a case of QS 5-30 at Home Depot on close out for 1.19 a quart, and I'm going to see how it holds up. http://www.lubereport.com/e_article000229004.cfm
quote:Maybe... I wonder about the blind faith put into the SM rating.
I dunno, Beans (Actually, I DO NOT know beans), but Mr. Dyson, Gary, and a few others here do, and they have all mentioned in the recent past that the testing SM oils go through to achieve SM rating is pretty severe and passing of said testing is such that only oil of pretty stern base stock will pass, regardless of brand. After the SM rating is achieved, I would imagine the differences between SM -rated oils are pretty much limited to the additive package of any given oil of SM-rating.
Check the online product data sheets, beanoil. They inevitably list meeting GM spec 6094M as well as various Ford and DaimlerChrysler specs. SM wasn't developed in a vacuum - it's a blanket API certification rating that was earned subsequently to test oils meeting the worst the contributing automakers could throw at them. "SM" takes up so much less space on the backside of an oil container than listing four U.S. manufacturers', six or so Japanese manufacturers', and two Korean manufacturers' individual specifications, don't you think?
For what my opinion is worth, I've used a couple of cases worth of QS 5w30 & 10w30 in my wife's '97 Expedition. It seemed as good as any other oil I've used in the Expy.
The first time I ever changed oil in the Expy back in '04, I bought a case of QS 5w30, because I recognized the name, & K-Mart had it at a reasonable price. I didn't know jack about oil back then. I relied on QS's advertising telling me that their oil was good.
With that said, I'd buy something different now, but not because I dis-trust QS; I don't. I just think that equal or better quality oils can be found for less than the cost of QS. Other than that, it's perfectly fine oil. Use it with confidence.