what oil to use in my rear end?

[sharkdog]

just wondering what oil I should use in my rear end my owners manual which is obviously 40 years old says use ford hypiod gear lubricant. Just wondering what that translates 2 in modern times. and if I have a stock 1970 f-100 with a 360-c6 2wd do you think it has a lsd in it/ how could I tell.

Thanks Pete

[67mann]

What fluid and how much needs to go into that badboy?

Fluid Type: 80wt or 90wt gear oil

Volume: 2-1/2 to 3 quarts approximately

Add friction modifer IF equipped with Trac-Lok, BUT NOT required IF Detroit Locker.

[Racer Z]

90 weight Hypoid gear oil. You can buy it at any auto parts store. Some of the new stuff is synthetic and won't mix with the real oil based stuff, so pay attention to what you get.

There are several ways to test for an LSD (limited slip differential). The best way is to remove the inspection cover and look for a clutch. If you find an LSD unit, then you will still need Hypoid gear oil, but read the fine print on the bottle, it will say that it is suitable for an LSD, or not. If it does not mention LSD, put it back.

If you use a non-LSD oil in an LSD unit, you risk burning out up the clutches. With burned clutches it will function like a standard open diffy. Some will chatter in the turn, others will not.

[Nitekruizer]

Lift both rear wheels off the ground. Try turning one wheel by hand.If the other wheel turns in the same direction it's Limited Slip. If the other wheel turns in the opposite direction it's not.

[Racer Z]

Lift both rear wheels off the ground. Try turning one wheel by hand.If the other wheel turns in the same direction it's Limited Slip. If the other wheel turns in the opposite direction it's not.

That only works on certain types of LSD units. Because of the different types, the best way is to remove the inspection cover and look for a clutch pack. If it is an LSD, it will be obvious at this point.

[STROKER69]

Racer Z

His truck being a 1970 F100 wouldn't that be a 9" rear and no inspection cover. I would use the old S.T.O.P. method.

That is to stomp on pedal from a stand still on pavement and see if you get only one or two black lines behind you, but be careful you might see blue lights also

[Racer Z]

Racer Z

His truck being a 1970 F100 wouldn't that be a 9" rear and no inspection cover. I would use the old S.T.O.P. method.

That is to stomp on pedal from a stand still on pavement and see if you get only one or two black lines behind you, but be careful you might see blue lights also

Hmm. That makes it hard to take a quick peek inside.

[69f-100]

Racer Z

His truck being a 1970 F100 wouldn't that be a 9" rear and no inspection cover. I would use the old S.T.O.P. method.

That is to stomp on pedal from a stand still on pavement and see if you get only one or two black lines behind you, but be careful you might see blue lights also

it should, mine is a 69 and it has a 9" in it..

[tnlprt]

it should, mine is a 69 and it has a 9" in it..

Do me a favor and post a picture of the removable cover on your 9 inch
If it is the factory rear the only plug is the fill plug in the carrier

[71fordkid]

I used motorcraft 75-140 full synth in my 9'' with a spool.