If this doesn’t convince you…

[RHOfan]

All RHO owners…get that rear differential fluid changed! Max miles would be 5000. 2500 miles is probably not too early.

Changed mined yesterday at 5082 miles & it glopped out of the drain hole like chunky maple syrup. Loaded with metal shavings (see photo). The new fluid is nearly clear…the old stuff looked like liquid graphite & smelled horrible. Even found a few chunks of cast iron (biggest was 1/4 pea size), likely left over from the axle housing manufacturing process.

It’s an easy job…easier than an oil change, since there is no filter. You’ll need 3 qts of 75W-140 synthetic ($20/qt for Mopar brand)…but you’ll only use 2 1/4 qt, unless you drip a little like I did. Drain plug is 1/4” drive, fill plug 3/8”. No plug sealant needed…the drain plug has a sealing washer & fill plug fits nice & snug on the rear cover.

Pro-tip: Make sure your fill plug is removed (not just loosened) while draining. It flows 3x better!

 

[RamFan]

Did you add back in the friction modifiers for the limited slip clutch pack? Not sure if the Mopar stuff already has it in it. That smells even worse than gear oil.

On a side note, my rear end is from Quick Performance in my Mustang. They advise against synthetics in the rear due to comparisons showing higher heat than when using conventional oil.

Food for thought.

Chris

 

[gram10]

mine was exactly the same around the same mileage, front diff and transfer case were a lot cleaner.

 

[RHOfan]

Did you add back in the friction modifiers for the limited slip clutch pack? Not sure if the Mopar stuff already has it in it. That smells even worse than gear oil.

On a side note, my rear end is from Quick Performance in my Mustang. They advise against synthetics in the rear due to comparisons showing higher heat than when using conventional oil.

Food for thought.

Chris

No friction modifier needed. It’s a locker, not LSD.

Ram specifies synthetic, so that’s what I am using. There are only a few applications I can think of where standard oil might work better, but not in a modern diff.

 

[kaos_859]

Not that its needed, but data from my 5K drivetrain fluid analysis reports fully validate and support @RHOfan 's suggestion.

Post in thread 'Oil Analysis' https://www.ram-rho.com/threads/oil-analysis.1384/post-32194

 

[RHOfan]

mine was exactly the same around the same mileage, front diff and transfer case were a lot cleaner.

I’ve drained my transfer case. Fluid “looked” fine, just a bit darker than the new fluid. A Blackstone report said 5K miles was a good fluid changing point for the transfer case due to the silicone sealer’s affect on the fluid.

I had a ‘15 Z06. Those were blowing engines until GM figured out the silicone sealer was deactivating the anti-foaming properties of the oil. They ended up changing the 1st oil change recommendation to required change at 500 miles, just to get the contaminated oil out of the engine.

 

[Deange2001]

All RHO owners…get that rear differential fluid changed! Max miles would be 5000. 2500 miles is probably not too early.

Changed mined yesterday at 5082 miles & it glopped out of the drain hole like chunky maple syrup. Loaded with metal shavings (see photo). The new fluid is nearly clear…the old stuff looked like liquid graphite & smelled horrible. Even found a few chunks of cast iron (biggest was 1/4 pea size), likely left over from the axle housing manufacturing process.

It’s an easy job…easier than an oil change, since there is no filter. You’ll need 3 qts of 75W-140 synthetic ($20/qt for Mopar brand)…but you’ll only use 2 1/4 qt, unless you drip a little like I did. Drain plug is 1/4” drive, fill plug 3/8”. No plug sealant needed…the drain plug has a sealing washer & fill plug fits nice & snug on the rear cover.

Pro-tip: Make sure your fill plug is removed (not just loosened) while draining. It flows 3x better!

did you just change the differential fluid (front and rear)? or did you do the rest of the drivetrain (transfer, transmission).

 

[RHOfan]

did you just change the differential fluid (front and rear)? or did you do the rest of the drivetrain (transfer, transmission).

Skipping front differential. I’ve heard few people report that being worth the hassle. Even Blackstone reported it being in good condition for another forum member after 5K miles.

Doing the transfer case. It takes 1.9 qts of $60/qt fluid, so waiting on Amazon to deliver some 1/2” OD poly tubing, so I don’t spill any fluid & end up needing to buy a 3rd bottle. The fill plug is behind an exhaust pipe, so rigging the fluid bottles with a pointed cap & poly tubing.

Also, the transfer case fluid plugs appear to be steel (maybe aluminized steel?) that thread into a cast aluminum housing. Be very, very careful tightening those plugs into such a soft material. I’ve noticed BW (transfer case manufacturer) uses blue RTV to seal the plugs without using much torque. The torque specs I’ve found range from 15-18 ft/lbs, with breakage occurring above 22 ft/lbs.

So, I’ve also ordered some blue RTV, and plan to use a very gentle touch.

 

[Scottie2Hottie]

Are you guys ordering rear differential and transfer case fluids from RAM parts dept?

 

[Sweptfever214]

Would that be changing it every 5k miles or just because it was wearing in?

 

[RamFan]

Would that be changing it every 5k miles or just because it was wearing in?

You should not have to. I changed my rear end fluid on my brand new 9" after about 4k miles on it and it looked A LOT better than what @RHOfan had. The company said after that, maybe every 25-30k miles or so.

Chris

 

[gram10]

Are you guys ordering rear differential and transfer case fluids from RAM parts dept?

i believe some use ram and a lot use amsoil

Would that be changing it every 5k miles or just because it was wearing in?

this is just an initial change to get out wear materials from initial break-in, I think is 30k intervals or more. It's in the manual

 

[RHOfan]

Are you guys ordering rear differential and transfer case fluids from RAM parts dept?

Yes, I did. They had what I needed & did not mark it up.

 

[RHOfan]

Would that be changing it every 5k miles or just because it was wearing in?

1st change at 5K miles to get rid of break-in debris.

2nd change can be based on your use case. Towing frequently or heavy off-road use, you can do 30K miles service intervals. Less demanding use…every 60K miles.

 

[Sweptfever214]

Thank you