Gear oil for heavy hauling

[ib516]

I have the 2007 Megacab in my sig. I have added some power to it, about 100hp, and it tows a 36.5' fifth wheel RV. I have noticed that at the end of every towing season, the paint on the rear diff cover seems to have flaked off the area where the ring gear slings oil at it. I have a PPE finned aluminium diff cover to install (that adds 2 quarts oil capacity). Here's a picture of one like it I grabbed off the www.

I have changed the gear oil every year, and always use the recommended 75w90 synthetic GL5 gear oil in the diff. Last time I think it was Catrol brand.

Anyway, before I take the old cover off and put the new one on, I obviously want to have the new oil ready, and I'll need 6 quarts give or take.

Looking for recommendations as to what brand to use, and what viscosity.
Some points to consider:
- The manual calls for 75w90.
- I tow 2 months a year
- I live in Canada, it gets cold here (-40*)
- truck is used as a daily commuter the other 10 months of the year

I have been considering Amsoil 75w110 as a nice comprimise between the 90 and 140. A little heavier oil when hot for better protection, but not the 140 weight. I don't want 75w140 due to cold weather performance.

75w90, 75w110, or 75w140...brand? -- Thoughts?

 

[ls1mike]

This is th 11.5 AAM rearend used in both GM and Dodge trucks or at least it should be. They are good unit. I have not really heard of any failures even with the 75w90 used. I would think you should be fine with the 75w110. Do you thing it getting that hot, I mean hot enough to flake the paint?

 

[ib516]

Yes I think it is getting hot. Truck & RV combined weight is about 21,000#, and I usually head to the mountains.

And yes it is the AAM 11.5" (3.73s).

 

[dparm]

Motul Gear 300 is a nice 75w90 with an extraordinarily high 222 viscosity index. It's billed as being for both race and street. GL-4 and GL-5 rated.

 

[deeter16317]

That is a common sight on the Dodge AAM...peeling paint.

The only thing I will say is research your brand...if you have an LSD. While they specifically tell you they don't require LSD additive, some people experience clutch chatter with certain brands of gear oil; which requires a few bottles of LSD additive to correct.

 

[ls1mike]

The additive is good stuff, in general I think it is pretty good for and LSD. GM tell you to use the stuff at least in my Trans am. Now I am not sure about the electric locking rear diff.
Does the Dodge have this?

 

[tomcat27]

personally I'd use Amsoil Severe Gear....
I've used Amsoil normal gear lube in mine for years
- granted I only have approx 13,000 lbs that I pull combined

 

[CarbonSteel]

Originally Posted By: ib516
I have been considering Amsoil 75w110 as a nice compromise between the 90 and 140. A little heavier oil when hot for better protection, but not the 140 weight. I don't want 75w140 due to cold weather performance.

The Amsoil Severe Gear in 75W-110 should serve you well.

 

[ib516]

Originally Posted By: ls1mike
The additive is good stuff, in general I think it is pretty good for and LSD. GM tell you to use the stuff at least in my Trans am. Now I am not sure about the electric locking rear diff.
Does the Dodge have this?

It is a limited slip, but doesn't require any additive as it has no clutches.

 

[JosephHarmon]

That doesn't look that heavy.

 

[ib516]

Originally Posted By: JosephHarmon
That doesn't look that heavy.


What are you talking about?

 

[DrDusty86]

Wecome ib,
This crowd is a lot friendlier than trailerlife..many helpful folks here..it wont turn into a trollinng bash fest either.
Dusty

 

[chubbs1]

Another vote for Amsoil Severe Gear 75w110. Arguably the best product Amsoil makes.

 

[deeter16317]

Originally Posted By: ib516
Originally Posted By: ls1mike
The additive is good stuff, in general I think it is pretty good for and LSD. GM tell you to use the stuff at least in my Trans am. Now I am not sure about the electric locking rear diff.
Does the Dodge have this?

It is a limited slip, but doesn't require any additive as it has no clutches.




While the Dodge spec says it doesn't need LSD additive, that Trac-Rite LSD indeed has clutches. They are termed "shoes" in the IPL and the Trac-Rite will indeed experience LSD clutch chatter.

I have one too (with almost 270k miles on it), trust me; they will get chatter with different fluids.

 

[MetalSlug]

I do use redline on rear diff, i know few guy towing some serious heavy towing, they all running redline gear oil. any car truck i own that using rear wheel drive, my choice alway redline gear oil. It never let me down.

 

[AzFireGuy79]

I have the same axle in my Dmax 2500HD and use RedLine 75w-90. Getting ready to add a cover here shortly.

 

[3311]

I'm using Mobil 1 75W-90 every 100k miles in all my trucks below. This a heavy(literally-batteries) commercial application as well . No problems.

edit: stock cover as well

 

[Jarlaxle]

I would use a 75W-140...everything I own (except my Jeep, haven't done it yet) gets that. I use Wal-Mart's Super Tech.

I would coat the cover with flat-black paint to better dissipate heat.

 

[ib516]

I ordered the 75w110 AMSOIL. Thanks all.

 

[ib516]

Well, I did the swap over the weekend. Here are some before and after shots:

Before, filled with 75w90 Motomaster synthetic:

After, filled with AMSOIL 75w110: