5W vs. 10W

[CougarRed]

So I live in Houston where it rarely freezes and often scorches. I've studied the VOAs of various 5w30 vs. 10w30 oils. Generally, the 10W oils are thicker at 40 degrees and:

1. Have a lower Viscosity Index
2. But a better NOACK score.

TBN, flashpoint, HTHS don't seem to differ within a particular brand's 5w30 vs. 10w30.

So is there any advantage to running 10w30 in my climate? FYI I have an engine (VQ37) whose heat that can shear 30 weight oils pretty good as well.

Many thanks.

 

[Johnny]

10W-30 tends to shear less than 5w30 because is does not use as much viscosity index improvers as the 5w30 does. One of the main reasons 5W-20 does so well, good base stocks and less VII.

 

[HTSS_TR]

Originally Posted By: Johnny
10W-30 tends to shear less than 5w30 because is does not use as much viscosity index improvers as the 5w30 does. One of the main reasons 5W-20 does so well, good base stocks and less VII.


I agree, specially with conventional oils. That why Honda recommends 10W30, not 5W30, dino for S2000.

 

[Old Mustang Guy]

Normally I'm a thin oil guy (5W20 in my Fords) but for your engine, which is thought to do well with thicker oils, I think 10W30 might be a good choice.

 

[5sfe91]

If you're sitting in a lot of traffic everyday and want a more shear stable oil that won't shear as bad go with 10w30/0w-40 if you're not in traffic and change your oil to nissan's OCI then stick to what they recommend.

OT: Are you a U of H fan COUGARred?

 

[CougarRed]

Originally Posted By: 5sfe91

OT: Are you a U of H fan COUGARred?


Yes - season ticket holder!

 

[mechanicx]

5W30 gives a minute advantage in cold Winter down near 0F or below with cranking and gas mileage during warm up where sheering doesn't matter much. So for cold climates in the Winter and doing lots of short trips, it is somewhat helpful but I don't think it has any wear advantage or lower pour point. In places like Texas where it rarely gets below 40 degrees, it doesn't offer much of anything and gives up a little for hot, high speed driving. I'd go with the 10W30 year around.

 

[Ramblin Fever]

I've tried using 5w30 in my Isuzu rodeo, even here in Colorado's temps where the winters can get brutally cold. My engine still shears a good 5w30 down to nothing; it gets 10w30 in the winter, and Rotella 5w-40 in the summer.

 

[mechanicx]

Originally Posted By: Ramblin Fever
I've tried using 5w30 in my Isuzu rodeo, even here in Colorado's temps where the winters can get brutally cold. My engine still shears a good 5w30 down to nothing; it gets 10w30 in the winter, and Rotella 5w-40 in the summer.


I can believe that with the the fuel shear and all. I guess my reasoning is 5W30 sheared down to 5w20 in Winter and low-speed driving may not be such a bad thing lol.

 

[znode]

Originally Posted By: Ramblin Fever
I've tried using 5w30 in my Isuzu rodeo, even here in Colorado's temps where the winters can get brutally cold. My engine still shears a good 5w30 down to nothing; it gets 10w30 in the winter, and Rotella 5w-40 in the summer.


That makes very little sense. Cold starts matter. That's the entire point of multigrade oils, and you're defeating the purpose.

 

[Alex38]

I'd run the 10w30 in TX with no worries, especially in the summer.

 

[mechtech2]

Texas is big.
Some areas would be better with the 5-30.

But Houston? A slight edge goes to the 10-30 in this special case.

 

[gfh77665]

Originally Posted By: mechtech2
Texas is big.
Some areas would be better with the 5-30.

But Houston? A slight edge goes to the 10-30 in this special case.


That is very astute. For example, the "panhandle" has a climate much more simular to Colarado's, than the eternally heated swamps of SE-TX and the drier but hot Rio Grande valley. Texas is huge. Just try driving completely across it one day!