Oil Weight?

[yukon25008.1]

I run rotella T synthetic in all my vehicles its 15/40 and/or 5/40. but im curious if the thinner the better? i talked to a guy who had a fleet of hd,s and said that these newer engines 6.0 8.1...,s have smaller oil passages then previous motors/trucks so i was thinking of using a 5/30 mobil 1.. regardless of the outside temps will the engine spin faster and easier with a thinner oil?

[Matt_]

run what the engine spec calls for.

 

What a lot of people don't realize is that oil can be too thin. Bearings will not get proper lubrication if the viscosity of the oil is below the proper threshold. Simply put, the oil won't "track up" through the whole bearing and therefore won't provide adequate lubrication.

[yukon25008.1]

understood.. the cap says 5/30, but 5/30 will be completly diffrent on an august day VS a day in jan correct.. do you run the same weight all year round?

[Zembonez]

Unless you live where is is subzero many many days a year, the 5-30 is the way to go. I run Amsoil 5w30 in mine and I live in a hot climate. No problems Summer or Winter here.

[Matt_]

The oil doesn't notice the difference in temp as much as our bodies do . 5W30 is perfectly acceptable for year around use. I think the owners manual calls out an optional oil to use for EXTREME cold temps but i cant remember it off the top of my head.

 

 

In the end, once your engine is up to operating temp there is no difference between a january and august day except that your cooling system isn't working as hard.

[yukon25008.1]

thats a good point.. i didnt think of that, yea im gonna switch to the mobil1 ulitmate 5/30

[yukon25008.1]

i just checked amsoils site.. they have a signiture 0/30 how different could it be from 5/30? would it be ok..or should i just stick with the 5/30

[Matt_]

IMO, there's no benefit to 0w30 over 5w30 in real life application. Sure... it looks better on paper in some instances, but i just don't see it materializing into any tangible benefit... and therefore, isn't worth the cost $.02

[dlstewart01]

Don't worry about the 0 being too thin....

0w, 5w, 10w, etc.is not weight but an somewhat arbitrary rating based on the oil low temperature flow and pumping characteristics - SAE J300 (1999) Motor Oil Grades- Low Temperature Specifications. I say somewhat arbitrary in that an oil that meets the 0w standard can be rated 5w or 10w because of the myth that "W" means weight ( it means winter) and 95-99% of the folks that recommend/sale/change oil believe this myth. We'll all heard "I would not use a 0 weight oil in your car.".

[yukon25008.1]

Thanks, im gonna go with the mobil1 5/30..

[Black02Silverado]

Mobil 1 5w-30 is a good oil. I think you might even see a little bit of a difference in economy, not much but you might since you are going from a 14w-40 to a 5w-30.

[yukon25008.1]

hey, im still gonna get the severe gear from ya..ive just been busy with stuff. so what kind of difference do you think i will see from 15/40 to the 5/30

[Black02Silverado]

You might not see any at all. Just that there is a small chance you will.

 

I saw 1mpg more on our 08 Acadia when I ran 5w-20 in it this summer. It seemed to start smoother and have better throttle response. I'm sure most of it was in my head.

[markw8]

A few years back, I've seen too many to remember, I was reading where the GM engineers felt that any oil with a spread greater than 5-30 was too much. Not sure if they didn't like the refining or the additive package. But enough things might have changed that this no longer holds true.

 

Mark

[jro909]

you were running diesel weight oil in a gasser? 5-30 is the best all around, i ran 10w-30 in my oil burner back in the day thats it...amsoil and mobil one are both great oil, had first hand experience with them both, the price is the crippler on the amsoil though