Rear end diff fluid change on 90 5.0

[Iwant5.0]

I need to know what to ise in my rear end when i change the fluid is 80W90 good and do i need to get friction modifier when i change it


thanks

 

[87'GTstang]

You need about 3 quarts of preferrably 75w-90 gear oil (synthetic will be worth it) and 1 bottle of friction modifier.

 

[88mustang_5.0sb]

My Mustang manual says that the rear end takes less than 2 qts of oil but...I put 2 qts in mine and it still wasn't full. Is the manual wrong? Do I need to add another qt?!

 

[Black1987Stang]

Keep adding it until it comes up to the proper level. im pretty sure when it comes out of the hole its good.i would also recheck in a few days, i heard the oil has to seep into the left and right axle tubes?(i think thats only when you dissasemble the rear) it should be fine but i would recheck it anyways.

 

[90mustangGT]

If you use synthetic you won't need the friction modifier. I would use synthetic because it is better and has a much better odor.

so let me get this straight, your going to pull the rear cover, just to reinstall it and fill it with new fluid? Please tell me you have a gear going in and at least a traction-loc rebuild going on.

 

[89MustangGX]

If you use synthetic you won't need the friction modifier. I would use synthetic because it is better and has a much better odor.

so let me get this straight, your going to pull the rear cover, just to reinstall it and fill it with new fluid? Please tell me you have a gear going in and at least a traction-loc rebuild going on.

Not all synthetics have a friction modifier, some require it be added. But just about anything will be fine in there, I prefer the lighter synthetic fluid like a 75/90, while others will run a heavier fluid.

I've changed my rear end fluid without doing any work myself -- I thought it was normal???

 

[HISSIN50]

i also like to swap fluid so i know what is in there.
Rockin just had a decent thread on this a couple days ago.
good luck.

 

[Rockin302]

I just filled my differential with Redline synthetic 75W-90 (comes with friction modifier) and used the Permatex copper RTV gasket maker and everything is good so far. The old fluid was pretty smelly, made me a bit nauseous, so make sure you do it in a well ventilated area becasue the smell lingers a bit. Although, I got used to it after awhile. You'll also need a 3/8" ratchet extention to get the fill plug out. make sure you get it on there squarely so you don't round it off.

Make sure you clean the gasket mating surface on the cover and the housing real well. Be sure to put about a 1/8" bead of RTV on the interior mounting surface of the housing. I also put a bead of RTV around each bolt hole as well as an additonal bead on the outside mounting area for good measure.

I used about 2.5 quarts of the gear oil. I filled it until it slowly came out of the fill hole and plugged it right up.

oh yeah, might me a good idea to use a bit of thread lock on all bolts.

BTW, I don't know if it's normal but my fill plug seems to be magnetized. I found a few tiny shards of metal but it didn't seem substantial enough for me to really worry,I couldn't see anything in the fluid I drained.

 

[88mustang_5.0sb]

Thanks for the info guys. I guess the Ford manual WAS wrong. I'll have to buy some more oil and fill it. And yes, I did pull the rear cover off, drain it and refill it without doing any gear changes because I just bought the car and wanted fresh fluid in all the right places. It looked good in there...no metal grindings. Thanks again guys.