Originally Posted By: kschachn
Originally Posted By: 40w8
Because in the old days they'd take a 10w and throw in Viscosity improvers (STP stuff) to thicken up oil.
That type additive tends to make hard carbon, shear down, etc.
Now they just build synthetic from Natural gas in such a way that it's specs are great like 0w40.
I was a fuel distributor selling industrial oils, and didn't need or know about 0w40 until 2008, but after reading uoa's I'm sold.
So today's GTL 0W-40 doesn't contain viscosity improvers?
It probably still does, but not to the degree used back in the day ... There is a thread on "Best SAE 30" here that has lots of good reading about oil development. It started as way to discuss oils w/o VII's at all. And along the way it drifted into mono-grades that can pass multi-grade tests like a number of Red Line products. But not all fancy oils can do this w/o VII's ...
M1 in particular has gone through many formula changes and is not the same as it was 10~15 years ago. Then it was all PAO based. Now, not so much. But it has built a HUGE fan base and it's still a good oil, so there is no-one saying don't run it. And the fan boys may not be oil people, and they still recommend it. That's OK, but it does biase the post count ...
A small dose of VII's may actually be a good thing. There are some indicators that VII's are good carriers of actual oil into high pressure environments. But they do get sheared and your oil does thin over time. Some engines are worse at beating oil, some don't do much. It is not straight forward as to what should be run where. Then there is sump capacity and external oil cooling as factors ...
An oil like Chevron Delo 15W-30 SD (severe duty) is a good compromise where you don't actually need a 0W or a 5W to get the motor started in winter
The thing to do is to look at your owners manual and disregard the W rating at first. Look at the op temp rating. If it calls for a 30, then judge how much cold weather help you need. If you live in SoCal or AZ, or TX - just drop in SAE 30. If you live in Minnesota, it's a whole nuther calculation ...