Is there a data plate/sticker on the '06s that has the info? My friend has a 99, and it gives him gear ratio, etc.

 

Pretty good read!

 

I have a friend that used RP in his 1997 Dodges front Diff and said he had some major problems and had to replace some seals, etc. He said no problem in the xfer case, or the rear diff. Has anyone else experienced this problem? He also said that you are not to fill fluid to the bottom of the fill hole, but leave it about an inch below to allow room for expansion, hot / cold.

I have a 2003 Dodge that has nearly 50K on it, and I am ready to change otu the factory fluid for RP in both Diffs. Any words one way or another that would fit my applicatoin? I am not sure what Axles I have. I need to look.

Thanks.

 

On many of the rear ends, there is "FILL LINE___" stamped on the cover. The line is around 3/4" below the bottom of the fill hole. You could miss the stamping if you did not know it was there.

Apparently they can blow seals if too full. The guy at the dealership said they fill fronts 1/4" below the hole, which if I recall from the manual is within spec.

I don't know about problems with RP. I have run Redline in both my trucks with no problems whatsoever.

 

I had the dealer do my first service to trans and both axles two years ago. They are one of the largest dealerships northern california and trucks are there biggest sales. They put in 75x140 in both and told me that this was recommended to them at there service training that year. They said the only reason your truck isn't factory filled with this is the heavier grade is more expensive $$ for dodge, and there is a slight negitive fuel economy difference with heavier weight and this impacts corportate reporting for EPA MPG BS.

 

Trans, trasfer case, and differential lube is a lot like motor oil in one respect - use the proper "weight" for the application.

Heavier oil than necessary does not provide any advantage, and does cause some disadvantages. Like drag, poor lubrication when cold, heat retention.

If you haul heavy loads and pull big trailers, then use the 140 - you need it. If you use your truck mostly as a daily driver, and occasionally haul a light load, then use the 90.

Pick the right tool for the job.

 

Yeah, I also run 75W140 in the rear, as recommended by the dealer.

Mostly the truck pulls the 5th wheel in the summer, and I can recall pulling the long curvy 6% grade in 110f temps...

I did not notice any change in MPG at all with the heavier gear oil. In theory there would be a drop, but I think rolling resistance and wind drag dwarf any loss to axle fluid.

 

1. You can but 75w-90 is more than sufficient unless your towing through death valley pulling 30k lbs on a 120 degree day 24/7, 365.

2. 15k is severe service, 30k is normal.

 

I PULL FAIRLY heavy 23000 lbs 32/33 inch tires, edge on 2 /3 changed oil at approx 55000 miles ,still very clean,no issues.

 

I recall when some said that Dodge changed to 75/140 back in 2007. I went to my local dealer and he looked it up at the Dodge dealer site and showed me that only the 8.5/9.5 inch diff in the 1/2 ton trucks was changed over to 75/140, that the 10.5 an 11.5 diff still use 75/90 gear oil. So any dealer that tells you Dodge changed over to 75/140 did not take the time to notice that it was only for the 1/2 ton trucks with the smaller diff.

BTW I know of hot shot trucks that only use GL-5 75/90 synthetic without any problems so I see no reason to use 75/140 being 75/90 work for well for them.