2003-2011 [Subscribe to Daily Digest] |
What he's trying to say is, he believes a smaller viscosity range provides better protection. What he's forgetting is that our turbos need as much High Temperature/High Shear (HT/HS) protection as they can get. The high heat (well over 500°F) & high speed (100k+ rpms) that the turbo's bearings experience will make short work of any oil not up to the task.
The first line of defense is the oil's ability to maintain a film over moving parts. This is where you'll get the best protection & least friction. The anti-wear (a/w) additives are there in case that oil film gets too thin. They provide a "buffer" before bare metal hits bare metal. The longer your oil can provide that film, the better off you are. And the heavier oils provide longer-lasting films. The easiest way to ensure you're getting the best film strength is to look for fully synthetic oils with an ACEA A3 (gasoline engine) rating. Typically, these oils require fewer a/w additives 'cuz the oil itself provides more protection (also identified in a report by the Japanese Automobile Manufacturer's Association).
Besides being durable, the other component to consider is the oil's ability to keep things clean. Presumably, all oils meeting the new GM Long Life spec have tons of cleaners & protection against acids. So, simply finding a full syn which meets ACEA A3 isn't going to guarantee an equal amount of life from the oil. Of course, any other premium full syn (PAO/Group IV) Long Life oil should do the trick here.
Shear stability is a red herring when it comes to these oils in this application. Yes, in situations where a low volume of oil is subjected to the HT/HS of a turbo engine, the 0W-40 has shown to shear just a bit more than other oils. But the keys to remember here are, 1) the 9³ SS is not a low oil volume application, & 2) it's always in a better condition to protect than an oil that starts out thinner to begin with. And when used in non-turbo engines, it's proven to be MORE shear stable than many oils, including some 0W-30 synthetics.
posted by 64.207.44...
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.