Why has M1 10w-30 shown to be better then 5w-30?

Messages
34,373
Location
NJ
I'm trying to figure out why Mobil 1 10w-30 is better then 5w-30? There practically the same oil but from all the UOA's, it seems the 10w-30 is better. It's not much different. [ July 06, 2003, 01:03 AM: Message edited by: buster ]
 

J

Messages
434
Location
Berkeley
quote:
Originally posted by buster: I'm trying to figure out why Mobil 1 10w-30 is better then 5w-30? There practically the same oil but from all the UOA's, it seems the 10w-30 is better. It's not much different.
10W-30 has almost no VII to help it cover the 20pt spread. 5W-30 needs a little viscosity index improvement to help it cover 25pt spread. [Cheers!] Jae
 

Al

Messages
19,255
Location
Elizabethtown, Pa
But also until the engine gets up to operating temperature the 10W will be slightly thicker. That probably results in less wear.
 
Messages
4,651
Location
The Garden State
Al, Unless you have an engine with "loose" clearances I would think that a thinner oil, ie, 5Wxx vs 10W/15W/20W/xx would cause less engine wear because in a "cold" engine it's circulating faster and easier than a thicker oil. Whimsey
 

buster

Thread starter
Messages
34,373
Location
NJ
I agree with Whimsey, I think the thinner 5w/0w-30's from M1 have there place in the newer, tightly built jap engines etc. I do tend to think though, that Mobil's VII's are more on the volative side then other brands. I have no idea how the 0w-40 does so well though.
 

Al

Messages
19,255
Location
Elizabethtown, Pa
But on the other hand-neither the 5W or 10W oil will get to the bearings for a couple dozen rpms. And the 10W oil left behind probably lubricates better than the 5W oil. Just a thought.
 
Messages
4,651
Location
The Garden State
With a cold engine chances are both the 5W and 10w have pretty much drained back to the pan, when using the same brand/quality oil. I still believe the 5W will still get to the parts faster and easier than the 10W upon cold starting. If your engine calls for 10W-30 I'm not saying use 5W-30. But if your engine calls for 5W-30, especially if it's an OHC engine, you're probably best off sticking with the 5W-30. Whimsey
 
Top