I think the original post should not have been done in such a misleading, haphazard fashion. Pennzoil and Quaker State conventional are API certified, contrary to the title of the thread. Quaker State and Pennzoil conventionals do have ILSAC certification where that certification can be obtained (i.e. 20 and 30 multigrades only), regardless of the confusion in the first post.
When someone complains that a specific oil isn't certified (talking ILSAC here since even straight grades have API certification), I would assume they're talking about a grade that is currently and normally specified for gasoline engines in North America and Japan. With respect to conventionals, the average 5w-20, 5w-30, and 10w-30 is SN/GF-5.
If one were pulling a straight grade, a 10w-40, or certain high mileage oils off the shelf, that's another matter altogether. Why not a 20w-50, a 15w-40, a 5w-50, some HDEOs, and monograde 40 to further confuse the issue?
10w-40 isn't called for in any new North American vehicle that I can think of. This is the whole point of the Starburst and the API Donut. It's so you don't put 10w-40, GC 0w-30, Delvac 1 LE 5w-30, Rotella 10w-30, and so forth into vehicles calling for something in a 30 grade with a Starburst. The first is the wrong grade altogether, and the latter three have way too high HTHS, not to mention too much phosphorous for the GC and Rotella.
