Rear Diff: Gasket, RTV or Both?

[V8BoatBuilder]

Hello,

I just pulled my Rear Diff cover to change the fluid, and I'm about to replace it.

I picked up a Fel-Pro paper gasket for the 8.8 at Pep Boys, but I did some searches and everyone seems to just use RTV. When I took the cover off, there were traces of RTV, no gasket. What should I use?

A side note, I'm planning on using Mobil 1 synthetic 75W-90 with 4oz of Ford LS additive - sound good? (The axle is a D4, 3.73 LS)

Should I put synthetic gear lube in the front IFS diff as well? Or would Hypoy C 80W-90 work? (I have lots of that in the garage)

Thanks,
Aaron

 

[zensius]

I just used rtv. No experience with synthetics, sorry.

 

[TarHeel085]

Originally posted by zensius
I just used rtv. No experience with synthetics, sorry.

same here, i just used red high temp RTV (my diff cover is red) an have had no leaking at all. RTV is the new way to go, its better than gaskets.

 

[dogfriend]

Factory Manual says use RTV Silicone

Installation (of rear diff cover)

1. CAUTION:
Make sure the machined surfaces on both the axle housing and the axle housing cover are clean and free of oil before installing the new silicone sealant. The inside of the rear axle must be covered when cleaning the machined surface to prevent contamination.

Clean the gasket mating surface of the rear axle and the axle housing cover.

2. Apply a new continuous bead of sealant to the axle housing cover.

Use Silicone Rubber D6AZ-19562-AA or equivalent meeting Ford specifications ESB-M4G92-A and ESE-M4G195-A.

3. Note:
The axle housing cover must be installed within 15 minutes of application of the silicone, or new sealant must be applied. If possible, allow one hour before filling with lubricant to make sure silicone has properly cured.

Install the axle housing cover.

1 Install the axle housing cover.

2 Install the bolts.

4. Fill the rear axle with Motorcraft Synthetic Rear Axle Lubricant FITZ-19580-B or equivalent meeting Ford specification WSL-M2C192-A and install the filler plug.

 

[V8BoatBuilder]

Sounds good guys, RTV it is. Thanks a bunch

 

[wpurple]

Gasket here

I used a gasket and a bit of RTV...seals like a champ but is a pain if you have to remove it (also a pain to scrap the old gasket off) but definatly gives the best seal.

Kurt

 

[biggs92EB]

ive had my rear diff cover off as much as my oil fill cap in the last year i have only used rtv and have never had so much as a little leak. as far as synthetic, well i was told in a different thread that being since i have ran plain ole 80-90w since day one that i should stick with it. so looks like people have gone both ways with good luck, good luck!

 

[V8BoatBuilder]

I belong to the "use cheap dino oil and change often" school, rather than the "use synthetic and change rarely" school. Both philosophies work, and both cost the same. But I don't like the idea of oil being in for a while.

But - my factory ford CD says "use synthetic" so I did. The only other place is the transmission's Mercon V, again, since the manual wants it. Otherwise, I'll just put good quality dino oil in.

Rear: 3 qts Valvoline DuraBlend Semi-Synthetic 80w-140. 4oz Motorcraft OEM friction modifier. RTV sealed the diff cover.

Front: 1.2 qts Castrol Hypoy C 80w-90 Gear Oil. Pumped out old oil with mightyvac.

 

[biggs92EB]

well you did it you inspired me pulled my x into the shop last night and changed my rear diff fluid and engine oil, my diff fluid was silver??????? i know some water got in, but silver? there were no metal particles whatsoever in the sump or on the fill plug magnet. any ideas? i just put in new bearings about 10K miles ago, and have changed the fluid since then, it was milk last time.