FYI: I went straight to the source:

http://www.bobistheoilguy.com/forums...2928338&page=1

Basically, it seems there are still some reasons for 10w30 - "A 10w-30 may become obsolete soon in the U.S. but as a synthetic it will have the best oxidative & thermal stability of all the 30wts and will hold up best at high temps. It has the least polymeric thickener, so it runs very clean. It's also the most shear stable grade in turbocharged engines due to the low polymer."

 

Nice.

 

First of all do we understand what the 0w ,5w and 10w means ?

 

I think we're past that point..? The question here is if there is any reason to run a 10w at all - even in "summer" temperatures the 0w30 oil is too thick for operation, but it will help minimize cold start wear far more than the with 5w or 10w oils, at the expense of, it seems, a small amount of stability.

The only reason I'm considering 10w is because that's the only weight (aside from 20w50) that ZROD is available in.

 

You mean winter and not weight, right?

 

._.

 

I know dude, I've been calling it weight my whole life, it was only recently did I learn that the W represents winter as it's a temp rating.

Cmon dude, why would I lie to you? I wouldn't **** you man, you're my favorite turd!

http://en.wikipedia.org/wiki/Motor_oil#Grades

Believe wikipedia or not, I trust 'em.

 

A thicker base oil will maintain its viscosity better. I have run amsoil 20w50 and 15w50 ZRod. I live in a cold area that goes into single digits on some occassions in the winter. After 40K miles using the thick oils I pulled my cams at 100K total miles and there was absolutely ZERO wear on the cam and caps. If there was anywhere the lack of protection would show up would be at the end of the oiling system. The thicker oil will protect your engine when it is being run hard and really heating up the oil. A bigger oil capacity and a bigger oil cooler would be nice for modded cars using stock weight oil. However with stock oil system and increased power I would say using thicker oils would help with higher power levels.

Now I had an STi and they are known to have oiling issues in the engines so I used some 5w50 Castrol Edge to help with cold flow because the cams and caps on all subarus I have had apart always have some marks on them.