Engine/Transmission (1998.5 - 2002) Diferential Friction modifier and synthetic??

[Motorhead]

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I need to change my rear diferential oil and want to switch to synthetic. I have a Dana 70 and how much friction modifier will I need with synthetic? What is a good synthetic? NO OIL WARS PLEASE:-{} .

 

[rluft]

I changed to synthetic and added 4 oz of modifier. This worked great.



I installed a Mag-Hytec but this time I did not add the modifier. When I pulled my trailer the next time the rear began chattering on turns. Since then I have added about 8 oz of modifier and it still chatters with no load when I accellerate around a corner. Some guys will tell you to do figure eights in the parking lot and if it chatters add modifier until it quit, I suppose that would work.



I would at least put 4 oz in. Better safe than sorry.

 

[klenger]

First time I put Amsoil 75W-140 in the rear end I did not need any modifier. I just changed it two weeks ago after 27,000 miles, and I had to add 4 oz. to get rid of the chatter. Dana 80 with Mag-Hytec cover.



I have a new bottle of Dodge friction modifier (unopened) that I will sell for $10, shipping included if anyone wants it.

 

[willyslover]

drain procedure... after you drain the rear end . . jack up eack side and get the tubes also emptied . .



Amsoil is a very good synthetic [and what I use]. . 75/90 is fine for our temps... unless you pull often then go to the 140 wt.



as to modifier. . fill to recomended level with the oil. . do a dozen figure 8 's each directiion r&l... then let sit a few min. re-check level..... then do some faster figure 8's each way and see if you have chatter. . if you do add the oil modifier 1 ounce at at time and then do the figure 8's again chatter add another ounce and re-do the 8's... continue till the chatters go away... . [I needed no modifier in my unit at all. . remember the factory doesn't set them all the same. . production issue



DO NOT ADD FULL BOTTLES OF MODIFIER at a time as you may over modify the diff. oil and then your "limited slip" will be as a open carrier as it will slip like the is no "limited"about it.

 

[RJOL]

Here's another option, and it already has the friction modifier in it...



http://www.coximport.com/royalpurple/

 

[Motorhead]

Thanks guys. It amazes me about the wide difference in the amounts of the modifier.

 

[Ram4Sam]

Worked for me...

Motorhead, I changed mine with Royal Purple(85-140w) and did not have to add any modifier, it works fine for me right out of the bottle. With or without my 5er hooked up, no noise, slips, or chatters. I got it from Jegs Racing, mail order.



Sam

 

[Motorhead]

Ram4Sam, Is the Royal purple a synthetic? Who makes it? Thanks,Chris

 

[Ram4Sam]

Royal Purple...

Chris, here is their website



http://www.royalpurple.com/



When I got it from Jegs, it was around seven dollars a quart and it is a synthetic.



Sam

 

[MGordon]

I just changed fluid in both axles with Amsoil Series 2000 75W-140. I didn't put any friction modifier in. So far so good.

 

[C Schomer]

I had to use 8 oz. of FM with Ams 2K75w90 and RP 75w90, 4oz. with RP 75w140 and none with RP 85w140. It seems like, the heavier the lube - the less FM required. Craig

 

[RJOL]

Originally posted by C Schomer

I had to use 8 oz. of FM with Ams 2K75w90 and RP 75w90, 4oz. with RP 75w140 and none with RP 85w140. It seems like, the heavier the lube - the less FM required. Craig

Has anyone else had to add FM to RoyalPurple gear oil??? It had friction modifier already in it.....

 

[Motorhead]

As Always..... Thanks Guys for all of the info. Chris

 

[mvaughn]

Ref: Royal Purple

I just changed to Royal Purple and so far I have not needed to add FM. Got my Royal Purple at J&M Speed Center in Riverside,CA for $6. 95 qt.

 

[RustyJC]

We tow a 5ver that puts us at 21,180 GCW (21,500 GCWR), so we went with the Royal Purple synthetic 85W-140. No friction modifier was needed - the RP has friction modifier as part of its formulation, and we haven't had any chatter, etc. from the LSD in the 12,000 miles since we switched to the RP. The rear axle is noticeably quieter when towing with the RP.



Got mine at my local NAPA - they keep the RP synthetic 75W-90 and 85W-140 on the shelf.



Rusty

 

[WadePatton]

I just switched to Valvoline Synthetic Diff Juice. (something like that) and am running ZERO friction modifier. There are threads on here under "LDS additive" and "friction modifier".



Zero. Change it and then add 1 or 2 oz at a time-IF at all necessary.



Mine hooks and slips just like it should.