Synthetic recommendations for 80W80 applications. (14 bolt, Dana 80, and SM465)

[GM Guy]

Hey everyone, I am getting ready to order a case of Gear oil from Amsoil via Wrecker, and I welcome his input as well as yours.

I am wondering what synthetic I should be running in place of 80w90 in a few rigs.

I read in my manual for my C3500HD that one is to change diff oil every 3K miles with 80w90. If one wants longer drain intervals, then GM recommends 75w140 full synthetic. I guess the reasons for these intervals is bad bearing geometrys that they new about from the start. something about the ring gear carrier bearings, IIRC.

The other applications are: the 14 bolt in the 96, the 10 bolts in the 91s, and the SM465 in the 91 diesel.

Is there an Amsoil product that will fit these apps, or should I run seperate ones for each application?

would this be good for everything? :http://www.amsoil.com/storefront/agl.aspx

or should I run that for everything but the Dana 80, and run this in the 80? : http://www.amsoil.com/storefront/svo.aspx

how does 75w90 or 75w110 work in 80w90 applications?

 

[GM Guy]

and then another question for Wrecker:

Are all oils under the Gear oil tab of the Amsoil Website full true synthetics?

The reason I ask, I thought there was a time when amsoil offered a cheaper blend, and I want to make sure I am not getting a blend.

Thanks!

 

[Wrecker]

First, yes all of the gear oils are true synths.

The Synthetic Gear Lube SAE 80W-90 (AGL) is ideally suited for large capacity differentials, semi trucks for instance.

The Severe Gear series is the best for you application. 75w-90 is perfect for nearly any differential that calls for 80w-90.

I recommend the 75w-140 Severe Gear in your C3500HD, and 75w-90 Severe Gear in the others. You could also bump them all to 75w-140 if you wanted to.

 

[btfarm]

Isn't a 300 mile gear oil change just plain nuts?!

 

[GM Guy]

actually 3 thousand, and yes it is. I guess you dont have to change it, but in the book it says if you do one of these things, it has to be the 3K interval: exceed 45 mph, load near GVWR, tow, basically what we all do with these trucks!

so what about the SM465 Wrecker? can I run 75w140, or should I use http://www.amsoil.com/storefront/agl.aspx this 80w90 replacement?

I think I am going to run 75w140 in all the pumpkins. especially on the Dana 80 cause it calls for it, and the 10 bolts cause the one is a little wore, and the diesel one needs all the protection it can get. and then since all the others are running it, might as well throw it in the 14 bolt.


Thanks for your input.

 

[Wrecker]

actually 3 thousand, and yes it is. I guess you dont have to change it, but in the book it says if you do one of these things, it has to be the 3K interval: exceed 45 mph, load near GVWR, tow, basically what we all do with these trucks!

so what about the SM465 Wrecker? can I run 75w140, or should I use http://www.amsoil.com/storefront/agl.aspx this 80w90 replacement?

I think I am going to run 75w140 in all the pumpkins. especially on the Dana 80 cause it calls for it, and the 10 bolts cause the one is a little wore, and the diesel one needs all the protection it can get. and then since all the others are running it, might as well throw it in the 14 bolt.


Thanks for your input.

I see no problem with running 75w-140 in the SM465, it calls for a GL-5/MT-1 gear oil. It's a little heavy but will not hurt anything especially since you will be running it in everything else.

Ashton