Engine/Transmission (1998.5 - 2002) Friction Modifyier w/Mobile 1 75-90

[WOT]

I just changed the rear end oil from Amsoil 75-90 (had 40K on it & still looked pretty good) to Mobile 1 75-90. I didn't use any friction modifyer with the Amsoil & never noticed any rear end noises/hop on corners. With the Mobile 1 I don't have any chatter but at low speeds & sharp turns (say about 1 MPH or less) I hear the rear end groaning a little (sounds like the friction discs rubbing together). If I don't have any tire hop should I bother adding some friction modifier to get rid of the groaning noise?



TIA!

 

[fox]

I'd say it is a personal choice. Mine needed the modifier. With out it it chattered and I was told the modifier was in it.

What ever you do don't add more than just enough or it will be too loose and act like an open dif.

 

[Texas Diesel]

I would add 4 ounces and then give it some time, add 2 ounces at a time after that. I put Mobil 1 in then added the OEM modifier too fast, 8 ounces was too much for mine, it slips a little now.

 

[LSMITH]

TD has the answer^^^^^^.



If the groaning is minimal try just 2 ounces to start. I run the Mobil 1 too, and need a ton of modifier. The only modifier that helps mine at all is the MOPAR brand.

 

[WOT]

All, Thanks for the input.



I have some Red Line Friction modifier handy, should I use it or get some Mopar stuff?

 

[Ramafid]

Get the mopar friction modifier. Save the headache of having to do it again.

 

[pkennedy]

Some quick reading here says that not all synthetics are engineered equal I run Amsoil 85-140 in yhe North and no modifier as recommended and no problems

 

[skerkvliet]

Just curious, why would you take out a 500,000 mile gear oil at 40,000, and replace it with a 50,000 mile gear oil?



Steve

 

[Texas Diesel]

Good point, some have used Mobil 1 with no modifier, try it first and see if you need it.



RE:

Just curious, why would you take out a 500,000 mile gear oil at 40,000, and replace it with a 50,000 mile gear oil? (what data do you use to support that claim????)



Read the post by gmorrison: (bottom)



https://www.turbodieselregister.com...threadid=38708&highlight=eaton+warranty+mobil



"If you bought a new Pete or KW the warranty on the rear ends would be 100,000 miles. If you have a receipt showing you put in Mobil synthetic 75W-90 the warranty is automatically extended to 770,000 miles with both Eaton and Rockwell. If both Eaton and Rockwell put that much faith into the performance difference that synthetic gear oil makes in hypoid gear life, it would seem to follow that it becomes a no-brainer for our comparatively lightly loaded rears. .

Also, Eaton/Rockwell recommend a 200,000 drain interval with Mobil 1. LE mineral gear oil is not on Eaton/Rockwell's listing, BTW.

The synthetic 75W-90 will provide a cooler running rear end, improved fuel mileage or power and a longer lasting rear end. Also, the Mobil 1 75W90 has the limited slip additive included in the formulation.

George Morrison, STLE CLS"





Not bad for a "50,000 mile" oil, any oil manufacturer can make unsupported claims but this a real evidence in favor of Mobil 1, I wonder if Amsoil is listed by Eaton/Rockwell is an approved lube.



The LSD plates wear and leave the clutch fibers suspended in the oil etc. The manual says even with Synthetic oil to follow schedule B if used in severe service.

 

[Gary - K7GLD]

Having been thru a NUMBER of these threads before, *I* rather suspect the difference is NOT so much in the lubricants used, as it is production variations in specific LS differentials - a relatively SMALL difference in friction material or spring tension can make a BIG difference in individual LS operation...

 

[Texas Diesel]

Gary, I suspect you are exactly right. I wish the Dana LSD's used coil springs as preload instead of bellville washers (SP?)

 

[WOT]

I changed it because I tow frequently & was more or less just curious obout it's condition compared to the stock stuff after 40K. I think I could have just left it in w/o problems (it was MUCH better looking than stock). I tried mobile 1 this time because I could get it easier & cheaper than Amsoil. Guess I should have stuck to what I knew didn't need additive. Ohh well, live & learn.



I just put 4 oz of MOPAR addititve in & I'll see how that does...



WOT

 

[andrewkoperdak]

I changed my rear oil at 30K. Call me a dope if you will but I thought it was time to inspect the rear end for wear and tear. I found that my lube was low out of spec. I stuck my finger in the fill hole and couldn't get it wet with lube. Not a good discovery in my opinion. There isn't any maintenance that I do early on my truck that I think is a waste of time. How many of you have adjusted your valves before the 150,000 mile interval?

I have also changed out my transmission lube and even changed my antifreeze. Once again, I found that my transmission wasn't filled as it should have been.

There is just too much dust and dirt out here in CA to put off maintenance.

I have a question for those of you who are using 75W90, why didn't you move up to 75W140? Are any of you not towing something with your truck?



Andy

 

[skerkvliet]

Andy,

You bring up a good point. (Though I prefer predictive maintenance over preventative maintenance). How much money could DC save by shorting every fluid reservoir, on every vehicle by, say, two ounces? Unless you're doing some serious off-roading in deep mud, water, or sand, I question how much dust and dirt is entering a differential, transfer case, or transmission. Thousands of lube analysis results in on-highway applications have shown dirt to be all but non existent in these type of applications. Engine oil, however, is a different story due to the fact that your ingesting air.



As far as your question regarding 75W-140 as opposed to 75W-90, the benefits of 75W-90 far out weigh the negative effects of 75W-140 for our application. In our trucks, using 75W-140 in the differentials will promote higher operating temps and increased fuel consumption. Remember this, a lighter viscosity lube, used in it's intended application, will take heat away from a tight tolerance quicker than a heavy lubricant intended for the same application. A heavier lube also puts more drag on the rotating parts. If you don't believe me, test this theory with an infrared gun. 75W-140 is really intended for low RPM off-highway use (dump trucks and loaders, etc. ).



My comment on an earlier post about Mobil1 being a 50,000 mile gear lube was a slam. I'm sure it will run half a million miles, however, I have seen analysis results on AMSOIL Series 2000 75W-90 with 1. 2 million miles on it that indicated it was good as new. I have compared both products in CTD's under load. The AMSOIL gear lube ran 12 to 15 degrees cooler than the same viscosity Mobil1.



steve