Help...9" Ford Rear end with Currie Trac Lok

[brgarris]

I have a ford 9" rear end with a currie trac loc differential. The guy that build my rear end put 75W90 Mobil 1 synthethc limited slip differential fluid in the rear end. After talking to Currie today they recommend using non-synthetic 85W140 gear oil (3 quarts w/4 oz of LS adder).

What are the cons for running the 75W90 synthetic fluid as I have done for about 150 miles? I have noticed that my rear end housing does get slightly warm to the touch and I have a small amount of fluid try to come out of my vent. I did not know if the synthetic oil would expand more under heat vs. non-synthetic oils or if it has more of a tendency to foam???



I plan to drain the synthetic fluid and replace with the recommended 3 quarts of 85W140 and 4 ounces of limited slip adder. Will this possible cure my venting issue? FYI...if you are looking at the 3rd member my vent is located at the 2 o'clock position. I have threaded a barbed fitting into the housing and ran a hose with filter approximately 8" above the rear end.

Have I damage the differential with the synthetic fluid?

Thanks!!!