That info was from LubiZol, not Mobil, and not specifically for the newly formulated 0W-40 oil. It probably reflects the general property requirements for diesels. Would be surprised if the new GM 0W-40 has those specific characteristics or sacrifices mpg.

The concern LDB raised is the high temp "viscosity improvers" that make a 0 weight oil 40 weight as oil temp rises are not stable for a full year in use. However he said he reserved judgement until he could see the SDS sheet and if it mentioned some of the components he expected. He admitted he was ~7 years out of the industry and things many have changed. Will be interesting to see what he finds.

Tadge said this in his comments about the change, "The Multi-grade Mobil 1 ESP Formula 0W-40 synthetic motor oil has many benefits including exceptional fast oil flow at startup along with low temperature pump-ability and exceptional viscosity/performance characteristics at high-temperature and high-RPM operating conditions."

From the quote in Bold, it sounds like Mobil, who it was said has spent years on this formulation, has found a way to make it work.

I still recall Dale Inman (Richard Petty's Crew Chief at the time) telling me they were using a double or triple 0 oil (or some such wording,) for more hp. When I asked if it was good for the engine, he smiled and said for the 500 miles we need it to be! That probably also gave more miles between pit stops, antiher crticial factor in NASCAR. They were building their own engines at the time!

 

Great info. So, in a sense you're saying, at least in racing, there are characteristics that are desirable which will sacrifice other characteristics, i.e., more HP may mean shorter engine life in your example. I'd like to see the "Lubrizol chart" for the new 0-40W that is being/going to be used on all C7s (maybe from Mobil).

 

^^^
Perhaps LDB, who posts here occasionally and is an "oil expert," will be able to comment when he has some data from their SDS. But I see no reason why Mobil could not have developed and oil meeting a diesel oil with mpg efficiency = to the non diesel oil spec!

 

GM and Exxon have still not posted fully consistent and clear data, so I don’t have any new info relative to my past posts. I’m also semi out of pocket until Wednesday so can’t do a multi-post exchange until then. But the key issue is indeed how stable today’s VI improvers are. When I retired in 2010, none were stable enough that I would use wide spread oils in my own car, but things can change. The key is whether Exxon and GM post enough info that we can deduce where things are in the spectrum from VI improvers being way better than they used to be, in which case the 0W40 would be all benefit with no regret, to still questionable, which would make it a compromise, valuable to those who tracked and/or changed their oil often, but a debit to those who didn’t track and ran to 0% on the OLM. Right now we can speculate about that answer, but don’t have enough consistent data to comment very intelligently on where in that spectrum the new oil is.

For general background, remember the issue with VI improvers. They are molecules with reverse viscosity behavior, meaning they get thicker instead of thinner as they heat up. They do that by looking like an octopus which, when cold, gathers its tentacles around its body, but when hot, extends its tentacles to their full length. That’s terrific as long as the tentacles are still there, but the problem is that they can break off, and once the tentacles are gone, you are out of luck. What started out as a 0W40 full synthetic is now a 0W25, or if it’s a dino oil, what started out as a 0W40 is now a 0W0.

 

"...For general background, remember the issue with VI improvers. They are molecules with reverse viscosity behavior, meaning they get thicker instead of thinner as they heat up. They do that by looking like an octopus which, when cold, gathers its tentacles around its body, but when hot, extends its tentacles to their full length. That’s terrific as long as the tentacles are still there, but the problem is that they can break off, and once the tentacles are gone, you are out of luck. What started out as a 0W40 full synthetic is now a 0W25, or if it’s a dino oil, what started out as a 0W40 is now a 0W0."

That is the clearest explanation of VI improvers and what can happen that I've read! Thanks.

 

Love the analogy! Sounds like Mobil may have found a bigger, stronger octopus or at least one that stays strong for 7500 miles or one year, whichever comes first!