2004 Ram CTD Gear Oil

[ant]

I will be replacing the gear oil in my 2WD soon, and I'm trying to decide on the best oil to use. It seems to run fairly hot even when not towing, I'd say near 150ºF, and the magnet collects quite a bit of "fuzz" in only 500 miles even after 17,000 miles.

The spec calls for a 75w90, and I'm now considering NEO 75-90 RHD, Motul Gear 300 or Amsoil Severe Gear 75-90.

Whats the best choice and would going to a 75w-140 reduce wear?

 

[TheLoneRanger]

Ant, it amazes me that vehicle mfgs spec the 75W90 weight in these heavy trucks. I think it's strickly for CAFE fuel mileage standards, and not for diff gear longevity. I can only tell you what I run in my Fords and Jeep: Synthetic 75W140 in the rear, and syn 75W90 in the front.

The only drawback to running the heavier oil is less mpg; that's worth it to me to get the added protection.

 

[Pablo]

You could go with with: 75W-140 Severe Gear

 

[1sttruck]

When I changed the OEM oil in the axles at 15k miles it looked like black snot. I refilled with Mobil 1 75W90, and at the next 15k miles it looked like a darker olive oil. I refilled with Mobil 1 75W140 and plan on using it for 30k miles. The 75W140 seems to make for less driveline rumble, it seems a bit more sluggish when it's below freezing, and it's kind of expensive. Next time I may do 75W90 in the front axle and 75W140 in the rear.

 

[Pablo]

I doubt it will run hotter, maybe very slightly - but it should thin less.

 

[ant]

Any comments on NEO 75-90 RHD or Motul Gear 300 ?

 

[ant]

Will Severe Gear 75w-140 run hotter than a 75w-90?

 

[unDummy]

Neo/Motul, IMO, are great stuff.

Your location doesn't really need the 'thinner gear oil', and most usually won't notice an MPG change in heavy vehicle anyway. I'd use a 75w140 synth.

Check with the local autoparts store. There are other choices that will work just as well without the higher prices of certain boutique oils.

SF makes an in-between weight. Its falls nicely between the 90 and 140 weight specs.