Tonight was the first time that I saw QS SynBlend 5W30 at my local Walmart. Both the Pennzoil and QS SynBlend oils are Dexos1 approved, but the Quaker State version is $1 cheaper.
QS SynBlend = $16.97
ST Syn = $17.47
After reviewing this Lubrizol Sell Sheet on the performance requirements of Dexos1 vs GF-5, I think the QS SynBlend is probably the better product at this price point for the following reasons:
- Dexos1 has a significantly tougher standard for piston cleanliness
- Dexos1 has a significantly tougher standard for Engine Sludge Protection
- Dexos1 has a marginally tougher standard for wear protection than GF-5
While it is quite likely that SuperTech Synthetic is being blended with a higher-quality base stock, the performance level of the additive package being used in the Supertech Syn is unclear. An oil's performance in the areas I mentioned above are going to be quite dependent on the additive system being used -- base stock alone will not deliver those results.
So, at least from a performance level standpoint, I am inclined to believe that the Quaker State Dexos1 blend is the better product at this price point since it has been tested (by GM) to achieve a certain performance level in some very key areas.
With that said, it is possible for SuperTech Syn to perform just as well, but without the testing (or even the blender's own endorsement) -- we simply do not know.
What do you guys think?

