Differential Fluid Change Intervals

[mberry]

... In my opinion changing gearbox oil is a waste of time. What is there to polute the oil? (and if you see filings it is too late anyway)...

For me, it's not about pollution in the oil. Over time and with as many heat cycles the oil is exposed to, the additive package will break down. It's worth it to me to change it regularly.

 

[Grizzly]

It is very easy.



All you need to change it is a 13mm socket and a torque wrench. The gasket is very high quality (rubber overmolded over a steel spine) and is reusable.



No need to flush, just drain it by removing the cover.



Torque in the Dodge SM is 30 ft-lbs, but I would go with 20 ft-lbs or 25 ft-lbs at the absolute max as they are 8mm bolts on the stamped steel cover and if you break one, then you have to get it out.



Front capacity is approx 3. 25 qts. Rear capacity is approx 4 qts. Both front and rear use 75W-90 synthetic gear oil. I use 75W-140 in the rear because I tow heavy 100% of the truck usage. You add oil in the pipe plug hole near the middle of the cover, until the oil comes out of the fill hole.



I usually paint my covers with flat black or semi-gloss paint, before I bought the PML cast aluminum covers which you can see in photo gallery...

Good luck!

Louis, thank you for your step by step procedure and your photo gallery.



Thanks to everyone who posted. All are very good and informative posts. It made me a believer in changing the fluid in the differentials and the aluminum covers. Would Geno's be the best place to purchased the covers?

 

[Jack in Alaska]

I just did mine about 2 hrs ago laying under the truck in a rainstorm, gravel drive and 40F. Not fun



I had 52k on my truck from new, old oil looked almost like the new oil. Almost clear, no smell and magnets had very minor deposits. Rear: 3. 8 qts. ; Frt. 3 qts. I bought 7 qts. and it is almost all gone. I used the MOPAR spec. fluid to preserve my warranty.



Have fun doing it.

 

[Wingate]

THoltz... Caterpillar makes them. I'm sure there are other people that make them also. They are great for monitoring heat levels without actually having to "be there when it happened"

 

[DaveHess]

Just throwing my 2cents in here... I change my transfer case and differential fluids out every 15K using Redline Synthetics (75w-90 in the front/80w-140 inthe rear). I won't use Amsoil as I blew a rear end up in my drag car with Amsoil in it. The car had Redline in it prior to the swap and it has Redline in it now. No Amsoil for me. Anyhow, I subscribe to the policy of it's cheaper to change fluid out regularly than to pay a repair bill. Even if the change out is considered too early or overkill. It helps me sleep at night because there is no way I can afford 55K for a new truck.

 

[CLynch]

I changed mine out around 10,000 miles. There is no filter in there and i believe the first change is the most important. Amsoil 75-110 in rear, 75-90 in front.

 

[WoodChuck]

I changed mine out around 10,000 miles. There is no filter in there and i believe the first change is the most important. Amsoil 75-110 in rear, 75-90 in front.

I second that. I changed all my fluids at 2k miles and then went by the schedule B intervals.