Originally Posted By: 1JZ_E46
You state that multi-grades are made for marketing reasons and provided one chart. I can't say whether you're right or wrong, because I haven't done all the research myself, but I tend to side with companies that have invested billions in developing robust oil specs (such as MB 229.5 or LL-01) that spec multi-grades, even in the hottest of climates.
Marketing might be one way to look at it, because there is a bunch of dumbing down. A manual shows SAE 30 as a suitable summer fill, someone here will do it in the winter and blame the OEM, or at least be looking for their help.
Beyond that, multigrades certainly are more than marketing. They're not marketing here. They're a sensible reality. It's either that or seasonal oil changes or dumping kerosene down the sump, and I'm not interested in that, and never have been. Additionally, if we're trying to push extended drains as a maintenance or environmental issue, it's kind of hard to tell me to run SAE 30 for three or four months here and maybe put not even half an OCI on the vehicle, then dump it for something multigrade for our giant winter. As I've said many times, in my applications, assuming no other overriding factor, if I can't run an oil year round, I'm not really interested.
It's also important to note that higher VI oils do contribute to fuel economy, so there's a minor benefit there from an OEM standpoint, even with a 0w-40 LL-01 over an SAE 40.
