The Chevron doc is especially interesting. It doesn't cover the scope of this topic enough, but it still helps. Thanks!
Again, I'd like some documentation. Just saying something is so on the internet doesn't mean anything without data to back it up. I used the Lubrizol oil spec chart. I'm not saying I don't believe you, but I did a fair bit of Googling using ULSG and extended/long drain oil keywords, and couldn't find anything meaningful about why C3 is considered long-drain, other than just "it is, trust us".
What I *DID* find were several references to C3 being considered an extended drain oil, which is cool. That helps, but I can't find a why.
You had an opportunity to educate me, and still do. But directing a backhanded comment at me instead saying "Hey himemsys, I know there's a huge difference in minimum TBN for these oils, but here's why ACEA C3 is considered a long drain oil despite the much lower TBN requirement" didn't help matters.
I already understand TBN is not the only method for expressing oil life. I understand oxidation is another tool for expressing oil life. That's one of the reasons I switched analysis labs to Oil Analyzers, to get that oxidation value. And finally, I already understand that whether an oil is considered "extended drain" or not, most oils these days can last 5k under severe use and 10k+ with light/highway use. It's possible, under the right circumstances for an extended drain oil to be done at 5k, depending on engine type, driving style and excessive short trips in harsh climates. And it's possible for a budget oil to last 10k+ under ideal conditions.
