Changing differential gear oil

Have not done the Bullitt, but all my other 8.8's and 7.5's, yes, remove the cover to drain the fluid.

They do not normally use a gasket, just RTv. I used blue Permatex rtv on my F150 on Saturday.

Filling it is the biggest pain, you may have to get one of those cheapie pumps to fill with, unless you get the car jacked up and the axle dropped down there will not be much room to get the oil bottle in there.

I'll do a quick hijack here...

The dealer told me the other day that I need to change my diff fluid at 30K miles. Is this a standard service interval? I haven't looked at the manual yet.

Thanks.

you know you will have to get a after market cover with a fill hole the stock one does not have a fill hole and yes you will need a pump to put it in pain in rear summit sells a cover with pan hard bolts for around 150.00 bucks good stuff

The OEM does have a fill hole... it's on the front of the diff near the top and it's a major pain in the ass to get the bottles up there to fill it without having the rear hanging down.

I believe the OEM says it's 100,000 mile change interval, but I changed mine with RP around 15k and will probably change it again around 30k.

mongo129 said:

you know you will have to get a after market cover with a fill hole the stock one does not have a fill hole and yes you will need a pump to put it in pain in rear summit sells a cover with pan hard bolts for around 150.00 bucks good stuff

Click to expand...

LMAO!

To the OP, remove all but the top two cover bolts. Loosen those two. You may need to gently pry on the cover or tap on it to get the seal to break. Let the fluid drain out like this (it will make less of a mess than if you just pull the cover off). Then, remove the last 2 bolts and pull the cover off. Throughly clean the gasket surface on the diff and the cover, and then clean any debris that you get in the dff (I just spray some brake cleaner to flush out the gasket material that gets on it). If the diff has a magnet, wipe the crap off it. Then use a rag and some brake cleaner to make sure the gasket surface is clean. Then, apply a bead of RTV to the cover, all the way around. Probably a 1/4 inch bead should suffice. I like to use RightStuff RTV, it is in a cheese-wiz can and works well. As far as the bead goes, some people like to just put the bead around the cover, making sure to surround the bolt holes. I like to put the bead, then spread it flat with my finger so that the entire surface has a coating of RTV about a millimeter thick. Then I remove any excess from the bolt holes. Then put the cover back on, bolt it on and tighten it up. You can put fluid in right away, but it wouldn't hurt to let it dry for a little while first. The fill plug is on the front of the housing near the pinion. Squirt the LSD additive in first, then squirt fluid in untill it pours out and put the plug back in. Sometimes you can get away with putting a piece of hose over the nipple on the gear oil bottle and using that to help you get it into the hole. Otherwise you can buy a cheap pump that screws onto the bottle.