Originally Posted By: cheetahdriver
sorry, but that is not the case. GM4718M does not require or even ask for testing by GM. what they do ask for is testing by a lab that has passed a proficiency testing program approved by GMPT (GM PowerTrain) Materials Engineering. there is no fee involved, but there is quite a rigorous requirement of paperwork, which is probably why quite a few pass it up.
as far as actual testing, there is a significant difference in the sequence IIIG (called out as such, not the IIIE as reported earlier) test. the % increase in the Kinematic Viscosity Increase @ 40°C is almost cut in half. other changes that jump out at me are the phosphorous amount is quite limited and there is a EOFT test that is a GM spec not listed in the ISLAC GF-4 spec. there are also some requirements about reporting changes in oil add packs and such.
there is also a low temperature pumping requirement not appearing in GF-4.
this is not a spec that i would think would be too difficult to pass with a good oil. OTOH, there are considerable paperwork issues, and some issues with substitutions. GM's spec, GM's rules. i will say that an oil that passes GM4718M is probably one of the more premium brews.
and, as i have said before, if GM doesn't list it on the list, it doesn't meet the requirements. it may be better, may be worse, you don't know, and there is no way to tell. one of the principal pains about this spec is that there are pretty rigorous requirements for reformulations. alot of boutique oils just aren't that consistent as to their suppliers. some are, and just don't want the paperwork hassle. but they don't meet the spec if they aren't on GM's list. period.
Not sure what to say. It does cost these oil companies to have their oil tested and they do have to pay to be certified. I find it humrous that you would say an oil doesn't meet a specification just because it isn't on the list. Man that is a riot. GM4781M is not a secret spec that we can not find out about. You can buy a copy of the spec online and then find out the test requirements and compare it to the spec's on the oil you want to use. If said oil meets or exceeds all those tests requirements then it meets or exceeds the spec and you are fine using it. Not being on GM's list does not disqualify it. The list means squat. It is just a place to go look for an oil that meets the spec so you don't have to research the test data yourself. I feel bad for people that think otherwise because you are mistaken and misinformed and are being locked into a small product group.
Under the law you are NOT required to use a certified product nor can any new car mfg void your warranty because you use an oil that isn't on their certified list. As long as the fluid you want to use meets or exceeds the specification in question BY LAW you have met your obligation to preserve your warranty. Royal Purple oil as an example meets or exceeds all aspects of the GM4781M oil standard and thus, despite not being on GM's list, is fine for use and GM would have to prove otherwise to void you. They couldn't do it as the oil would pass their test with flying colors.
You also said...
Quote:
it's when they start doing the infamous "meets or exceeds" that we start having problems.
Why do you consider meets or exceeds to be infamous and the start of problems? It is the LAW and just how things are. If their product meets or exceeds the spec in question they have every right to let people know.Why pay to have it certified if you already know it passes?