How hot is hot? (rear end)

[wsurf]

Greetings, new subscriber. I have read quite a bit on the AA rear axle concerning lub type, fill height, etc. I have a 03 DRW with about 1600 mi on it and hooked up the 5th (it was empty) and drove for 100 mi to check things out. The 5th is very light (5600 lbs sopping wet) and I drove about 50 mi one way climbing to 4000 ft elevation. At the turn around point I put the palm of my hand on the diff. cover and it was hot! Could only keep it there for 1 sec. Have never done this before with my Ford so I do not know if that was ok or not. Have not check fluid height, no rear end noise and was driving 55 to 60 mph. Truck was built in May. Any thoughts, should I get it checked out or is this normal?



Sorry for the long post, so far love the truck, got tired of the "other" truck.

 

[dgieson]

I have a temp sensor in both diffs the rear runs about 170* empty and about 185* with my horse trailer in tow 15k+.



Dave

 

[jimnance]

I am not certain if the lubricant that Dodge fills the diffs is a full synthetic or not.



Either way, 180 F wouldn't alarm me.



However, synthetics have proven to be the most cost efficient lube for heavy duty over the road trucks due to greatly extended oil change intervals. Also, full synthetic lubes are more resistant to break down at high temps.



If the Mopar fluid is not synthetic then I would change it at the first recommended interval.



I happen to favor high quality standard petroleum base stock oil for the engine because they have proven to be the most cost effective lubricant for heavy duty diesels. For transmissions and differentials I favor synthetics for the same reason.

 

[sag2]

On a hot day and after towing both my Ram and my Ford motor home get very warm. Some day I should grab the Ray-Tek and check the actual temp. I would guess it is in the 150-180 degree range. Both have synthetic lube.

 

[wsurf]

dgieson, Thanks for the numbers and would explain why I could only keep my hands there for a second. I like everyones recommendation about fluids and will do my homework when it comes time to change the fluid out.

 

[dnitzel]

I would say that if it BURNS your finger(s), it's too hot. That's what I tell trainees at work when checking gear boxes, motors, and compressors. If you can hold it for one second, and depending upon the oil, the ambient outside temp and if it's been under a load, and no finger burn, it's warm. Many devices like gear boxes run warm. I would guess that regular 80W-140 gear lube and axle seals should be good for at least 250-300 DEGF. 300+ DEGF should slightly burn a finger, outside paint may peel.

 

[Deezul1]

You might check oil level as several members have reported very low fluid levels from the factory.

 

[wsurf]

Agree with your comment Deezul1, but would have to ask what is the right level (?) considering all of the threads about the rear end diff. fluid. If any one knows the correct level I would appreciate it (for a 2003 QC, DRW, 48RE, 4X4)