I'll be putting Amsoil Gear Lube 75/90 in both diffs and t-case. I had good luck with it in my last D2, I wasn't having drivetrain noise issues but when I switched to the Amsoil it was even quieter going down the road than the 9 month old regular Castrol it replaced.

 

I don't even think I would move up to 140 even given those conditions. The extra noise is usually excess lash between gears and the thicker oil only works to quiet down the chatter by putting more drag on the gear set. It doesn't flow as well between bearing surfaces which is where it matters. Not thay it's not important to lubricate the gears but once you have the excess lash the gears will just continue to wear, making it quite won't reverse or stop that.

The 90 weight was spec'd because of how it flows at the average differential operating temperature.

 

Thanks. I am convinced now 75/90 I know everyone has their own brand choices. How often should you change gear oil?

 

I think that synthetic is worth it just for the peace of mind. Not to mention the quieter drive train.

If you are doing a lot of wading or water crossing then you will need to change the diff oil more often. Or if you are doing a lot driving in sandy, dry desert areas.

 

Thank you. I don't do water driving or sand. I live in Austin we dont have too many rough terrains

 

the synthetic is the best in my opinion either way. Can withstand the heat and friction better in that aspect and a longer service interval. I'm in central Alabama and don't do any wading or sandy driving but I've have better luck with synthetics but to each it their own.

 

who's got the best Synthetic 75/90 i need 7 quarters to fill all three, right?

 

I vote Redline and you should get 7 quarts. I just ordered (2) gallons of redline from Amazon.

Don't forget, you need a pump to get the oil into the diffs and transfer case.

 

Does Redline makes their own or OEM from other suppliers? just curious

 

www.redlineoil.com

Since 1979, Red Line Synthetic Oil has grown to manufacture more than 100 quality products, including motor oils, gear oils, assembly lubes, fuel additives, and its popular WaterWetter cooling additive for the automotive, motorcycle, marine, and industrial markets. Based in Benicia, California, Red Line has a reputation with racers and enthusiasts alike for creating products that perform and protect better than any on the market, regardless of price.

Founded by president Tim Kerrigan (retired) and the late Peter Filice to produce lubricants for the racing industry, Red Line Oil now distributes its diverse line of products across the globe. The company brings a knowledge of available technologies and responds to technical challenges, satisfying the high demands of the performance industry. Red Line's employees are enthusiasts that stay on top of each racing and performance niche, ensuring that product recommendations allow customers make the significant performance gains.

Red Line formulates fully-synthetic oils and chemically-advanced additives using the world's finest base stocks. Rather than cutting costs by blending in petroleum products, Red Line's motor oils and gear oils use superior ester base stocks that provide extreme stability at high temperatures and superior film strength at lower viscosities where more power can be produced.