I'm at 15k miles and it's time to do the rear gear oil. I'll be towing 12k on occasion so I'm thinking of using the 75W140 Royal Purple. Will Dodge have an issue if I use this weight instead of the 75W90? I do not want any warranty issues. Thanks.

 

It is not the recommended weight, but guys that tow heavy have been using it. Haven't heard of too many rear end failures with it. Biggest issue has been some clunking in turns after using the heavier weight, and even though it is not required, for some reason using a friction modifier helps to eliminate the clunking in turns.

 

It'll work better if you tow a lot, but if its not seeing a ton of towing, I'd stick with the standard 75w90.. I'd also re-think royal purple though too..

EDIT: If you read page 19 of this:
http://www.amsoil.com/products/gearl...hitePaper.aspx

You will see that royal purple came in almost last in the tests, just in front of mopar synthetic and lucas oil...
Scott

 

I would re-think the royal purple as well and go with amsoil 75-90 or 75-110 severe gear oil its alot better than royal purple ,just my .2 cents worth.

 

How much would my 03 2500 rear end hold? How often should it be changed? Thanks in advance!

 

The rear end in the 2500's holds around 4 qts.. I changed mine at 40k miles, and don't plan to change it for at least 50k more miles, but I used Amsoil 75w90 severe gear, which is good for up to 100k miles or so...
Scott

 

Pep Boys had a book that said the 11.5" rear holds 4 liters or 8.4 pints.

 

sounds about right.. IIRC, mine was about 3.5 quarts in the front and just over 4 quarts in the rear, which would be about 8.4 pints.
Scott

 

I just changed mine with about 30,000 on it and towed 10,000 lbs about 10,000 miles of that 30,000. The oil came out looking like the day I put it in. I am going to 40,000 on this oil. With the increase in cost of oil if I can SAFELY extend the 15,000 mile interval I want to extend it.

 

According to the 2005 Factory Service Manual, it's exactly 122 +/- 1 ounces, which is just under four quarts.

 

If you put syn oil in, do you need any additives to it.

 

Not unless you get some chatter.Most do not.I had to add it to mine using the 75w90 Amsoil Severe gear oil.All info says its NOT needed in the AAM differantial but that seems to be not the case all the time.

 

Just changed mine to shaeffer's 75w90 syn. at 35000 miles. Tansfer case too. Going to do the trans at 50000.

 

I don't know about other synthetics, but with Amsoil its not needed.
Scott

 

2Rowdy what did you put in the transfer case? I hope ATF+4.