Synthetic gear oil for trac-loc? Capacity? Proper weight?

S

Stealthy96

Registered
Hello All,

I am purchasing a 3.73 trac-loc pumpkin from Max at 5-Star Ford and would like to use Amsoil synthetic gear oil even though I know the unit comes shipped with Ford gear oil.

However, I remember reading a post about not using synthetic oil for trac-locs but can't seem to find this thread in the archives. Can I use synthtic oil? If so, what is the proper weight and capacity? Amsoil offers 75W-90, 80W-90 and 75W-140.

Amsoil also has the slip lock additive in 4oz containers. Should I use 1 or 2 of these or should I stick with the Ford additive?

Thanks!
Al

96 MK8
 
RE: Synthetic gear oil for trac-loc? Capacity? Proper weight?

I can only tell you about my experience with my truck which has the 9.75" rear with trac lok. Ford recommends synthetic 75w140 with one bottle of additive. Mine started chattering or making a noise because it did not want to release in the corners. I replaced the fluid and additive and it didn't help. I then found out about a TSB that Ford put out on the trucks and Expeditions that said if they chatter replace the clutch pack and shim it 0.010" less. I then found out the right rear axle seal was leaking so I had to dump the fluid again to remove the axle. The parts guy at the dealer said put two bottles of additive in to get rid of the chatter. I did and the chatter is gone. By the way, this synthetic fluid (75w140) was only available at the dealer for about $13 per quart. My diff takes 2.6 qts which is the same as an 8.8" diff.

I wonder what two bottles of additive will do to the gears????

Roadie
95 Champagne Mark VIII
00 Ford F150 Supercab 4x4
02 Mazda Protege
86 Chevy Monte Carlo SS
81 Honda CB900C
 
RE: Synthetic gear oil for trac-loc? Capacity? Proper weight?

I recently installed a 3.73 Traction-Lock pumpkin that I also got from Max @ Five Star. I installed it less than 2 weeks ago and it has been trouble free. I did not drain the factory oil or anything. I just used it as it was shipped. I don't get any chatter or anything. The "posi" itself is very smooth.

Max did ship me an extra little bottle of the friction modifer and gave me the part number for the synthetic oil too. They can't ship hazardous stuff I guess. Here is the exact part number that Max supplied to me: XY-75W140-QL

Max ships the extra friction modifer in case you want to drain the oil and refill it after a break-in. BTW, don't forget the DOOZ-17271-B 21 Tooth speedo gear. Max will provide this though. I have verified, via a GPS receiver, that your speedo (stock size tires) stays perfectly accurate too.

I'd just install the pumpkin and not worry about changing the oil. It comes with synthetic oil in it so I don't think that Amsoil will help. Feel free to contact me directly for some install hints.
 
RE: Synthetic gear oil for trac-loc? Capacity? Proper weight?

When I installed my 4.10s, I researched this. Amsoil synthetic and others are advertised as compatible with all traction locks as is without friction modifier.
 
RE: Synthetic gear oil for trac-loc? Capacity? Proper weight?

Stock 8.8" rear diff holds 1.5 qt's. I use AMSOIL fluids, it's cheaper, and still maintains the warranty. Not to mentin, it holds up better in the long run. AMSOIL also ahs a friction modifier for their fluids as well, also cheaper than the stuff at the dealership.
 
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