which gear oil should i buy and what weight i know it calls for 75w140 but can i use 80w140

 

https://www.f150online.com/forums/19...fluid-use.html

 

thanks see im installin a posi rear end and i needed to know but let me ask this do you have to use fords friction modifier or can i use the stuff from advance auto parts that is friction modifier or does it matter

 

Ford - XL-3 - four ounces. Good stuff

 

k thanks do you think walmart supertec 75w140 will be ok its synthetic and a bottle of friction modifier

 

Sure. How much would you be saving over say Motorcraft lube?

 

i dont know i cant find motorcraft lube like ive been lookin all over the internet and cant find it all i know is tht supertec is 10 dollars a quart and ill get the friction modifier off ebay

 

Get the modifier from a Ford dealer - by the time you pay for shipping it will be cheaper.

You only use the Ford modifier with a Ford limited slip - anything aftermarket, use the vendor's recommendation for both lube and modifier.

 

oh ok thanks so i can use the stuff from advance its called like k&w posi trac trans x friction modifier and its 7 fl ounces and do i have to use a full synthetic

 

If you are using stock Ford gears and a stock Ford limited slip, you must use 75W140 full synthetic, ANY brand, and you should get a bottle of modifier FROM A FORD DEALER.

If you are using aftermarket gears and/or an aftermarket limited slip, use what the AFTERMARKET MANUFACTURER requires.

 

im getting a aftermarket lsd im useing the same gears

 

with an aftermarket l/s, you need to follow the manufacturer's specs.

you no longer need to follow ford's instructions for the rear end.

what setup did you go with?

 

just the stock gears and im getting advance auto parts to order the posi for me its from motive gear for 348.00 and ill just get some suppertech at walmart full sinthetic and posi trac friction modifier at advance auto parts and thanks for all yall help

 

No, you need to find out from Motive what to put in there for lube and modifier. Please read what we are trying to tell you!

 

I know if you use a True Trac, you don't need any friction modifier.