Gear Oils

[Benson]

Are most of you using Amsoil 75W-90? Are those of you towing doing alright with this oil?

 

[chuck3]

So far so good, haven't had it in that long but seems fine, my TT only weights around 7k.

 

[Big Jon]

This has been a source of frustrating confusion for me. I even posted a question about it last summer, and everyone must have been on vacation because I didn't get any real definitive advice.



Both a local truck mechanic that I've used for years, and the service manager from the dealer I purchased my truck from have said to stick with the factory fill 90 wt. The local mechanic has gone on to say that synthetics just do not hold up well in a differential, and that he had seen several fail after 25,000 or so miles running on synthetic. I wish there was some better data on this, because I want to run whatever lubricant will provide the greatest protection.



Jon

 

[Bob Cochran]

I used the 75w-140 but have only had in for 2 weeks and have not towed yet with it. Seems to work okay and did not need any friction modifier but I heard some do. I bought some just incase so if it still works okay after couple of more weeks will return to NAPA.

 

[JJW_ND]

Synthetics and Gear boxes are meant for each other!

No petro fluid will mach synthetics for all around service life, protection, and operation under extreme temperature conditions. There are some high quality non sythetics but even they have pretty conservative cold weather limits.



I can tell you a good sythetic 75W90 will be more fluid then the 15W40 petro engine oil at -25 temps.



I have had very good luck with full synthetic 75W90 in my 96 5sp differentials. I sample the oil every 30K and change evey 30 - 50K. Samples very good with low iron and TAN even after 30K. Have over 200K with lots of extreme towning in summer heat to arctic cold. Several years back, I spoke with Dana light axle tech support and was told NOT to use the 75W140 in northern climates. They stated nothing would be gained over a good 75W90 synthetic.



Had one rear seal changed under warrenty at 15K. Changed to Synthetics at 20K. Still have the same seals.



I know I am not the oil one sampling rear differential oil, I would be interested in those testing other gear oils in our trucks and the type of driving you do.



Dodge is the the only light truck of the big three to NOT require full synthetics in 2500's and 3500s from the factory and for warranty.





jjw

ND

 

[Bob Cochran]

Norhtern climates!!!! Not a problem.

 

[amsoilman]

BigJon,

A few years ago, 1992 I believe, I read an article in a trucking Magazine called "Overdrive". The article was called "Slippery Solutions". Within the article it was stated that "Correct lubrication is critical to the life of truck transmissions and axles, and selecting the right lube would greatly enhance life and reduce maintenance costs as well as down time. " The article went on to say that Eaton and Navistar both firmly recommended that lubes in transmissions and axles should be more expensive, but more reliable "Synthetics". They based this on years of testing, and backs their recommendations with high mileage warranties.



Eaton customers using Synthetics have the advantage of extended warranties up to seven years or 750,000 miles, with a change interval recommended at 250,000 miles. They went on to say that if a petrolium product was used, the warranty only covered 250,000 miles with drain intervals at 50,000 miles.



I think both Eaton and Navistar spent a lot of money to come up with these conclusions, so I think perhaps the mechanic maybe doesn't know about "Eaton or Navistars" recommendations.



Wayne

 

[paccool]

I put Eaton in my truck a couple of months ago. Even with additive the rear is ratchating pretty hard in the corners. Have Royal Purple ordered to put in and if that doesn't work then it will be Amsoil. (I know, I shoulda went with it in the first place!)

 

[Wcr25]

Originally posted by Benson

Are most of you using Amsoil 75W-90? Are those of you towing doing alright with this oil?

I went to Amsoil 75W-90 at about 1000 miles on my 2001. 5 Auto. I also put on a Mag-Hytec rear cover at that time. I pull a 10-11K pound 24" enclosed trailer. Haven't had any issues with anything in the drive train. Of course had the DTT stuff put in the transmission at 1800 Miles. Some people just don't understand yanking out a perfectly good transmission @ 1800 miles to do a complete overhaul! Had the master kit from DTT put in as well. (Mopar-Muscle and Massdiesel in Mass. ) While those guys had the beast on the lift, I yanked off the front cover and went to the Amsoil at that time. Kept me out of their hair and something to do. I have right at 11k miles now and looking to go to Amsoil 5W30. Plan on extended drains with analysis.



BTW, towed heavy in 95 degree weather several times over the summer, no issues, even @ 75 mph.



Todd