What synthetic gear lube do you use in your rear diff?

[SHobbs]

Royal Purple 75W-140 since new.

 

[LRutigliano]

I recently became an Amsoil temporary dealer...



I put Amsoil Severe Gear 75W-90 in both axles and also in both axles of the Durango.



I had Royal Purple Max Gear 75W-90 in the front axle and 74W-140 in the rear and noticed two alarming observations when I drained it (with only 4k on the lube):



1) Both axle magnets had some fine black residue on them. More than I felt comfortable with. Never noticed this with Valvoline or Mobil 1 75W-90 synthetics. Also, since the front axle is just spinning and not producing and power, the fine residue really surprised me.



2) The 75W-140 came out like maple syrup and it was over 65F in the garage. I honestly thought the axle was low on lube (it wasn't) with how slow the old lube came out.

 

[steved]

Holy digging up posts from 2001!!!

 

[Gumpertz]

Amsoil all around

both differentials get Severe Gear 75W-90

 

[Silver_Ram]

I had Amsoil 75W-90 Severe Gear in both pumpkins, last weekend I switched to 75W-110 & so far no fuel mileage decrease. I had previously tried 75W-140 & also noticed a fuel mileage decrease.

 

[wneubauer]

Just put Mobil 75-90 in the front today. Put Mobil 75-140 in the rear in December... I replaced the same Mobil in both diffs. All's well so far.

 

[DaveHess]

Redline on both ends! 75W-90 in the front diff and 80W-140 in the rear. I am going to drop down to 75W-140 in the rear during the next MX due to our winter temps here. I love Redline!

 

[Quass]

Royal Purple, Max Gear 75/140

 

[Matt400]

Amsoil prices

For those using the Amsoil 75w140, what are you having to give for a quart of that stuff?

 

[Wiredawg]

I use the following:



Factory Fill (Probably Valvoline synthetic) 2009 4500

Valvoline Synthetic 75W-140 2003 2500

Lubrication Engineer 75W-140 in 2002 3500





Wiredawg

 

[MegaTony06]

FYI for AAM 11. 5 Rear Differentials:



AMSOIL tech service hotline recommends 75w90 as recommended due to the AAM rearends being "finicky". They specifically do not recommend going to a higher #/ heavier weight.

 

[steved]

Hmm, finicky means what??

 

[Cowboy]

rp means royal purple, rp 75-140

 

[JDoiron]

I have a 2002 quad cab 2 wheel drive with anti-spin differential. Can I use 75-140 royal purple gear oil in it? I use Royal Purple engine oil and want to put it in the rear end. What Royal Purple should I put in the transmission when it is ready to be serviced?

 

[steved]

I have a 2002 quad cab 2 wheel drive with anti-spin differential. Can I use 75-140 royal purple gear oil in it? I use Royal Purple engine oil and want to put it in the rear end. What Royal Purple should I put in the transmission when it is ready to be serviced?

Yes, you can use RP 75w140... my dad has RP 85w140 in his D80 and has had good results.



Not sure about the transmission fluid, never had to look it up.

 

[steved]

FWIW:



I'm standing here changing the gear oil in my truck (the 11. 50AAM). I just drained about 8 quarts of probably completely fine RP 85w140, there was almost no fuzz on my rare-earth magnet (super strong pull), and the fluid looked as good as the day I put it in (it was still purple). The funny part is that fluid was changed last at 80735, and the truck currently sits with 212820. I'm filling with Schaeffers #167 75w140 full synthetic, and don't plan to touch it for at least another 100k.



I had to ditch the cover gasket as it had started to rust and swell... just did rtv. Keep in mind, I have a high capacity aluminum cover from ORU... so my results may not be typical.

 

[DGamelin]

I have had some problems with the diff in my 04. We have used Valvoline most of the time and other big names in the shop. But when my 04 used up a diff at 55k and the new one started with metal filling wright away. I started looking for something different trying different one with each run. Then I read a about a shear test that was done on gear lubes buy some independent company, for what I don't remember. They were all vary close like 1 or 2% of each other, except Castrol synthetic had something like a 16% better then 2nd place they didnt say why just gave the numbers. We can't get Castrol around here so I had to order a 5gal pail of it. I got 80/140 and 75/90 synthetic I use the 140 the difference in fillings was obvious on the first run Castrol is all we use here. Our truck is used for hauling only it has a trailer on it 90% of the time. The pozi in the 3rd gens are prone to this when pulling heavy. Because of how it works with that helix gear thats why they have a 15k oil change recommendation. If you tow a lot I would stick to it.



_________________________

93 250 2wd xc 354 auto 273k

04. 5 3500 4wd qc dully 373 6speed 100k

 

[jshumate]

I currently have LE 607 in the diff. When I change it, I will use the replacement for 607 which is LE 1605. Anyone tried it yet? I hear that it is a full synthetic.