It really doesn't make a lot of sense to have a different spec for every OEM out there. They are not that diverse in what they make or the base materials they make them from. Heavy commercial truck OEM's take a more realistic approach.... they may have their own alphabet soup of a oil spec, like Detroit 93K218 or Cummins CES 20081 or Volvo VDS-4, then they come right back on the same page and all agree that API CJ-4 is appropriate. They even allow a wide range of choices like 5w30, 10w30, 15w40, and 5w40 for their engines used in similar working applications. Two heavy trucks side by side, doing the same work, one using a 10w30 and other a 15w40, and both doing fine. And this is on engines that will be worked hard their life and be expected to go well into hundreds of thousands of miles or nearly 40,000 hours without a major repair. They all have their unique "approved oil" listings, but I have yet to see a heavy commercial OEM deny a warranty over what oil was being used in the rare case of an engine failure under warranty. That on engines that cost as much or more than most folk's personal vehicle.
It is because of my many years of experience with commercial engines that I waste so little time on whether I use only an oil that on some anal retentive auto OEM's "official approved list". I just select a quality oil that meets the latest API and ILSAC specs, of a syn blend or better that is a good value and call it a day. Since owning my first vehicle, a 1966 Chevy C-10 in 1970, I have never lost an engine or had a major failure that can attributed directly to oil. Both personal and commercial versions.
