Differential Fluid?

[91LTDProject]

This is pissing me off. All I need to know is what weight of fluid to run in the rear end of the Lincoln, I cant find anything on shopkey besides capacities and our fluid reference books only go back to 1996. And yes, I did do a search first to try and find what I was looking for.

[91waggin]

What kind of Lincoln are you talking about? When I did the rear end in my 91 MGM, I seem to recall putting in 80W-90 gear oil, but when I look at my online service manual for the same car, it says SAE90 gear oil.

Also, don't forget about the friction modifier if you've got a Trac-Lok.

[marquisman]

my books say around 3-3 and a half pints depending on rear end

[87_crown_vic]

supposedly you can use just full synthetic gear oil and not need the friction modifier stuff... though i would still use some. go with the synthetic to help it from being so thick in the winter to help economy wise and in summer it dont break down as bad. it isnt like regular oil changes in it... take good precautionary measures and save from headaches later.

[91waggin]

I believe Royal Purple has the friction modifier built in. But I still think it's either 80W-90 or SAE90.

[Lincolnmania]

80w90 a little over two quarts

[DuceAnAHalf]

i put just straight Lucas heavy duty gear lube in the 85's rear, In the 97 i used Mobil 1 both cars have trac-loks

[gadget73]

80w90, or you can use 75w140 synthetic, doesnt matter much. if its a traction lock, you're supposed to use the friction modifier with conventional oil, i'm not sure about with synth.

[mrltd]

I run mobil 75-140 without modifier.

[gadget73]

mine is wallyworld 75-140 with modifier. might not be neccesary but i guess its not hurting anything. trac-loc is quiet and works *shrug*

[91waggin]

80w90, or you can use 75w140 synthetic, doesnt matter much. if its a traction lock, you're supposed to use the friction modifier with conventional oil, i'm not sure about with synth.

What I was told is that a lot of the synthetic oils have the friction modifier already mixed in, such as Royal Purple that I mentioned earlier. When I read the label on the back of the Royal Purple there was something about friction modifier already being in there, but the conventional stuff I ended up going with didn't say anything about it, so I added the friction modifier, and have had 30k-ish of trouble-free driving.

[mrltd]

I guess I should clarify "no additional friction modifier" in mine.

[91LTDProject]

Axle code in the Linc is 5, so its a 3:27 open differential, no friction modifier needed. Thinking now I should have put this in the drivetrain section. Oops.

[cld783]

i think i just filled mine up to the fill hole. I used 80w90 and didnt use any modifier.

Add rear axle lubricant to the carrier to a level 1/4 - 9/16 in. below the bottom of the fill hole. If equipped with limited slip differential, add friction modifier C8AZ-19B564-A or equivalent. Install the filler plug and tighten to 15-30 ft. lbs. (20-41 Nm).

[87_crown_vic]

when i werked at wally werld, i would use the drain plug torque wrench and torque to 20