Ford 8.8 Diff, Break in Oil

OiledMustangGT · May 6, 2004

I have a V8 mustang w/ the 8.8 w/track-lock LSD in the rear. It has 3,000 mi on it since new.
In the past I have been told it is a good idea to change the gear lube at 5,000-10,000 mi to get all the metal shavings from the gears "breaking in" and everything getting set in place.
Would this be a good idea, or a bad one... the ford guy said to never change the axle lube, but I have always done this in the jeep w/o problems

btw, I plan on using Redline 75W-140 or Royal Purple full synthetic lubes

SteveD2 · May 6, 2004

The ford guy doesn't have a clue what he's talking about. You can never change the oil too often in anything.

mikep · May 6, 2004

quote:

Originally posted by ZmOz:
The ford guy doesn't have a clue what he's talking about. You can never change the oil too often in anything.

I'd be inclined to agree that the Ford guy is clueless. Just like the Ford service manager who told me there is no reason or benefit to changing brake fluid....ever.

sbc350gearhead · May 6, 2004

Change the lube at about 5k. You will be surprised at the crap that comes out. Unless you are constantly running slicks, I think you would be better off with a 75w90.

novadude · May 6, 2004

I use Mobil 1 75W-90 w/ one bottle motorcraft friction modifier in my '95 GT.

crashz · May 6, 2004

Change the lube out in my 8.8 at 65K. Lifetime fill may ***! I wish I had camera. There was a ton of gunk and shaving in there. It looked like some dumped a cup of graphite in the the diff. I will be changing it again soon. Probably to Amsoil 75w-140 if I can.

MolaKule · May 6, 2004

OMG,

As others have stated, it is a good idea to change differential fluid sometime shortly after 5,000 miles. After that, I prefer changes every 30,000 miles, and change the differential about the time as I change the Automatic Transmission fluid (if so equipped).

I work closely with a differential rebuild/repair shop that also races modified stock cars, and people come in for service and complain about their differentials making noise, and I mean clacking, groaning, whining etc. We find they have never changed the fluid and the mechanics laugh when they say the dealer told them the fluid was a "lifetime" fluid. They drain the lube and then shine a bright light into the differential and differential cover and show the customer what lifetime fluids DO NOT do.

The customers are then told that new bearings and shimpacks have to be replaced, and possibly the drive pinion and ring gear.

pinoy99 · May 6, 2004

Ya know, changing diffy fluid might be cheap insurance especially if the transmission has drain/fill plug or at least put one's mind at ease but IMO not necessary on ALL vehicles.

Had a mustang gt '88 ragtop 5sp manual - diffy ran flawlessly for 225+k miles on oem fill - car was driven hard (read: burning rubber constantly,cross country trips etc).

Current truck - diffy got serviced as per manual but had an R&P changed from 4.3 to 5.38 - that replacement gears only lasted about 100k even with periodic maintenance - hopefully the current ones will last a long as the rest of the truck.

Just my $5 worth.

OiledMustangGT · May 7, 2004

yeah, I'll definately be changing it.

Are there any reasons NOT to go with the 75W-145? I realize gas milage will be a little lower and I might lose a few HP, but I thought it would provide better protection for extreme conditions.

You cant really blame "normal/average" people all that much for not changing it b/c the owners maual usally says something like "The axles are lubricated for life, it should never be replaced" or something to that effect.

MolaKule · May 7, 2004

As to the 75W140, I would be concerned about LSD locking in cold weather, unless you assume that the diffy is warmed-up prior to "burnout."

ssmokn · May 7, 2004

I think 5 to 10K is way to long. I like to drain for the first time at 1K and then every 25 or 30K after that.

The 75W140 works fine in Ford's with limited slip. I'm running that now without problems (even single digit temps over the winter).

JohnBrowning · May 7, 2004

You know I think that a good 75W90 will work just fine! RP MaxGear 75W90 does 100Lbs on the timken test with 75W90! Their are not too many 140 Wt gear lubes that can do much better then that! You would be giveing up gas millage HP and cold flow for dubious returns.

RL 75W90 will take care of business as well!

When I live and played in 120F heat I ran 140Wt in everyting andit worked fine. If I had been in more moderate climate I dobt it would have made a good choice!

OiledMustangGT · May 13, 2004

thanks, but I'm going to stick to the specified lube for now due to the warranty.. I don't want any hassles at the stealership

jsharp · May 14, 2004

quote:

Originally posted by novadude:
I use Mobil 1 75W-90 w/ one bottle motorcraft friction modifier in my '95 GT.

That's exactly what went in mine the last time the Trac-Loc was rebuilt. Too bad it's making bad noises now and the whole rear needs rebuilt. ;(

And before anyone asks, I don't thing the lube caused the trouble. It's probably the only reason it's lasted this long...

Gary Allan · May 15, 2004

quote:

the last time the Trac-Loc was rebuilt

D35?? D44? Trac-Loc is a Dana LS...

Nitrox · May 16, 2004

Wow, the man. is recommending 75w140 in an 8.8 rear? Manual for my '92 8.8 said 75w90. All 8.8 rears for Mustangs are the same internally. I changed the oil 1000 miles after installing new gears and diff. Put in Redline 75w90.

MNgopher · May 16, 2004

F150's using the 8.8 have speced 75w140 since the '97 model year.

The 8.8 went behind all 4.2l V6 and 4.6l V8 equipped F150's prior to the new body style in the '04's. (5.4's got the 9.75"). I haven't paid attention to the new rigs.

OiledMustangGT · May 20, 2004

hehe,I was out at tha auto parts store today to see if they possibly had RL gear oil, no luck on the shelf, so I asked the guy behind the counter if he had RL or royal purple in 75W-140 he was like "yeah I have some good stuff for you WAYYY better than that royal purple" proceeds to show me Valvoline gear oil?? I'm like "I need someting a little higher quality" proceeds to show me LUCAS gear oil ...OMFG!!! this dude CANNOT BE serious

I give him the rolleyes, then he goes on for like 5 minutes telling me this is the best stuff out there. Granted I have not read up on their heavy duty gear oil here, but I am pretty sure the royal purple is some of the better stuff. I have RP in the jeep right now and it has been my fav. so far(ran the valvoline once and then coastal once each, absolutely hated both..noise/whining)
Am I crazy or is the Lucas garbage? plus it was like $6.50/pint which is in the RL/RP price range

Ford 8.8 Diff, Break in Oil

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