Okay so I have an 05 f150 with a 4.6. It does not have a limited slip rear end. I just bought full synthetic 75w140 gear oil... problem is... the bottle says limited slip on it. I assume I'm safe but would like some reasurance. Thanks.

 

Most guys say to go ahead and buy the friction modifier just to be safe. I'd put the oil in and see if you get any chatter from the rear end before I bought the FM. You don't want TOO much in it either.

 

Both the LS and non-LS use the same diff lube, the only difference is the addition of the friction modifier. You will be fine. Adding friction modifier on a non-LS is kind of useless, as it only affects the clutches., but will not hurt.

 

Missed the part where you said you don't have LS.

You'll be ok like kingfish said.