Rear differential fluid low?

[TechHeavy]

While getting my oil changed at my favorite 10 minute-type place, (because of the cute female mechanic who likes my MM) I was told that my rear differential fluid was low, and black. They suggested a flush and refill. I said, "Wait! Don't touch it... let me talk to the boys online to see what they're doing."

So, is there any special fluid you guys recommend, or just use the spec in the manual?

Thanks for the input. :)

[RF Overlord]

So, is there any special fluid you guys recommend, or just use the spec in the manual?This is a good time to install the shiny heiny...!

The manual calls for 80W-90 conventional. When I had the 4.10s installed last summer, I had Mobil 1 75W-90 synthetic put in. That's what I'd recommend if you're going to have it changed, which is a very good idea, BTW. Better yet, do it yourself; it's wicked simple, although a little smelly. Buy 3 qts of M1 75-90 for $6.95/qt at AZ, and get the Ford Racing re-usable gasket for $8.95, and you'll be stylin'.

Here's the interesting part: when the blower and shiny heiny were being installed last week, we noticed the cover now sported a tag I don't remember seeing before that said "75W-140 Synthetic"...I don't know if the tag was always there and I missed it (maybe, but doubtful) or if the dealer who performed the axle TSB a few weeks ago put it there. Since I planned on using Motorcraft 75W-140 synth after the blower installation anyway, and that's what I provided the techs, I guess it all works out. I'm a-gonna haveta call the dealer now and aks them wassup wit' dat...

[BillyGman]

I worked in one of those places, and I had to quit after one week since they were so dishonest and routinely ripped off their customers by telling them they needed things that they didn't as well as charging them for oil filters that were never replaced during oil changes on the cars that had oil filters that were hard to get at!!! I wouldn't let those places ever touch my car let alone the rear end fluid.And how did they know that the rear end fluid looked "black"??? BTW, I use the 80W90 weight. That's fine for me.

[Rider90]

I worked in one of those places, and I had to quit after one week since they were so dishonest and routinely ripped off their customers by telling them they needed things that they didn't as well as charging them for oil filters that were never replaced during oil changes on the cars that had oil filters that were hard to get at!!! I wouldn't let those places ever touch my car let alone the rear end fluid.And BTW, how did they know that the rear end fluid looked "black"???

I'm with Billy on this. I've seen it happen first hand, and all I still hear are stories. Why was she inspecting your diff oil anyways?

[BillyGman]

Remember one thing....they get a commision to sell you things in those places.

[RF Overlord]

Why was she inspecting your diff oil anyways? I thought most quick-lubes check all the fluids...? The local Jiffy Lube the company makes me take my van to always checks the diff and the front axle & transfer case (it's AWD)...

[RF Overlord]

TechHeavy, I just noticed your sig...since you're Trilogised, I change my recommendation to 75W-140 synthetic for you...75W-90 for N/A cars...

[TechHeavy]

Remember one thing....they get a commision to sell you things in those places.
But, she's CUTE!
Ok, Billy, and Rider90... I hear ya on this. But this is a reputable place that simply has a checklist of things to check on vehicles. They check these things on every vehicle, (I think) that comes through. I've been going to them for years. I trust them and they treat me right.
Just so you know, I had the mechanic in the pit come up and show me the fluid, and it was very dark...
I don't mind flushing and changing just to be sure. Anything for my baby! I just needed to make sure about the type of fluid to change to.
RF, your recommendation for 75-140W is noted! Thank you sir! :)

[Rider90]

Maybe you're right Dave. I just don't let anyone that I don't trust, for example, the L/M Dealer or any quick-lube place, for any reputable information without futher consultation from a trusted source. I do my own oil changes and I maintain my car. The only time my car has been to the dealer is when I bought it, and it has never been to a Jiffy Lube or any other equal fast-lube for as long as I own it.

Maybe this gear oil change will make a difference when you take me out for a spin after I crash at your house for a few days :D

[BillyGman]

Dave, you trusting soul you. Okay, I warned you. ;) BTW, why do you think that they have that chica working there? That's a very deliberate business move on their part. I can assure you that.

[TechHeavy]

...without futher consultation from a trusted source. Maybe this gear oil change will make a difference when you take me out for a spin after I crash at your house for a few days :D
That's why I'm posting it here my brotha... to get the scoop! :) Dayummm man! I'll let you drive me for a spin when you crash at my house! :D :beer:

[carfixer]

RF, the TSB kit to fix the axles comes with 75-140 synthetic oil and the tag.

My dad lives 1500 miles from me so he brings his car to Jiffy Lube. He got the "your diff fluid is dirty" pitch and bought the service. The tech forgot to put the mark on the diff with his grease pencil. 3K miles later, he get the "your diff fluid is dirty" pitch again. He says WTF, you just did it. They said "never mind". The diff housing is now marked with a number on the diff with a grease pencil. Buyer beware! Do the service per the owner's manual.

[RF Overlord]

RF, the TSB kit to fix the axles comes with 75-140 synthetic oil and the tag. Thanks, 'fixer...I was beginning to obsess about it...that makes me feel much better! :woohoo:

[Marauderjack]

A friend of my Daughter had her oil changed in her older Escort at a local "Jippy" Lube and the motor locked up after about 10 miles!!!!! :mad2: :argue:

They found that the tech had used the wrong "bulk hose" and installed 80W90 gear oil in her crank case!! :censor:

After 2 months they finally replaced her engine but it was a terrible fight and she had no car during her 2 month battle......she finally rented one and the "Jippy" guy had to pick up that cost as well!! ;)

I NEVER GO TO THOSE PLACES......BULK LUBRICANTS ARE VERY RISKY!! :o

Marauderjack :bandit:

[Petrograde]

I've been going to the same Kwik Lube for almost 2 years. I take my own Mobil 1 and Motorcraft filter. So far so good. They have never tried to sell me something I didn't need.

But,.. I do talk to the guys, the new guys always have questions.. and I'm happy to answer them. I've built a rapport with some of the guys,.. They even noticed when I showed up with the wife's Honda! :o

When I had my first oil chance there,.. I stood right in front of the bay and watched the whole time,.. I think this tends to keep 'em honest. Besides, if they are shady, they are less likely to pull a stunt if they realize the owner knows a thing or two about his/her ride.

[JimmyXR7]

Bulk fluids are bad if you have novices or incompetents working at Jiffy lube. Many people heard about the lady who added diesel fuel to her gas powered car. I can just imagine how much gasoline would cost if it was sold in 5 gallon cans!

I have been driving muscle cars for years and really like my MM. The muscle cars always ran with 80-90W diff oil. I would think that the higher rating would be valuable after a long run when the oil is hot and then you floor it. The sudden power could make the gears thin the oil film or even touch.

On my older muscle cars the wheels would spin and limit the loading. Since My MM is a 300ab, the traction control would limit the slip, but I am still not sure if the full shock load of power would hit the differential?

Jim

PS - I, not Jiffy lube, change the differential oil on all of my cars every 90,000 miles even if they do not need it. What is the period for the MMs?

[SergntMac]

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Dave, I replied to your e-mail, it bounced, so Ive copied my reply here.</PRE>

If you refill with Motorcraft 75-140 lube, you'll need to add a 4 oz. bottle of friction modifier, available at any FMC/LM parts counter. A while back, someone here started a rumor that synthetic lube did not require this modifier, but I'm not sure if this is true today. This additive allows the rear end to "slip" properly in hard turns, and without it, you could damage rear end internals. RFOverLord posted great advice. Considering the power on tap with a Trilogy kit, this may be a good time for you to inspect and improve your rear end. He called it a "shinny hinny", but it's really superb reinforcement for the differential. I suggest you open the rear end and inspect internals for wear and tear up to this point. Flush it out, and while it's open, install a Ford Racing/Dana 60 bearing cap stud kit (M-4034-A, $37.95) and rear end girdle (M-4033-G1, $195.00), and I'll tell you why.At 16,500 miles on my Marauder, my rear end came apart. Three ring bolts came apart, one lodged between the ring and the pinion, one went to the bottom of the housing, and the third almost punctured the OEM cover, left an impression looking like a bullet wound. The Richmond 4:10s were done, and the OEM TractionLoc diff destroyed. The repair was over 1500 bucks. I bought an Auburn diff, Ford Racing 4:10s, stud kit, girdle, new axles, new bearings all around, and Motorcraft lube with modifier. 10K miles later, not a hint of a problem, and I am pushing 434 foot pounds of torque into the rear end on a daily basis. I wish I had the chance to take some preventive measures first, they could have saved me 1200 bucks.</PRE>

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[RF Overlord]

I, not Jiffy lube, change the differential oil on all of my cars every 90,000 miles even if they do not need it. What is the period for the MMs?

Jim, the MM manual states: "Rear axles are considered lubricated for life when the vehicle is used for normal service."(ahem...bulls**t...cough...) Manufacturers want people to think their cars never require maintenance, so they tell you things such as transmission fluid and diff lube never need changing*...

*...except under special circumstances(...cough...crapo la) :rolleyes:

What most people don't realise is that "lubed-for-life" actually means the life of the warranty, not the life of the car. I think it's good insurance to change the diff lube every 30,000 miles...even using top-of-the-line synthetics such as Mobil 1 or Amsoil, a complete drain and fill costs less than $40 and takes about 20 minutes...less if you get the re-usable gasket.

[JimmyXR7]

[QUOTE=RF Overlord]Jim, the MM manual states: "Rear axles are considered lubricated for life when the vehicle is used for normal service."(ahem...bulls**t...cough...) Manufacturers want people to think their cars never require maintenance, so they tell you things such as transmission fluid and diff lube never need changing*...*...except under special circumstances(...cough...crapo la) :rolleyes:

Jims reply: I agree with you that sooner is better than too late.

Modern gears are case hardened and the gear oils are good and in the southwest with the wide open freeways, (away from LA, San Fran/Bay area, phoneix, etc) the cars get a lot of easy miles. If you go to the drag strip, I would change the diff oil more often and use the multi-grade diff oil.

The transmission fluid I like to change at 30,000 miles with the newer overdrive clutches. What does the MM manual say? How often do you plan on doing it?

Jim

[RF Overlord]

The transmission fluid I like to change at 30,000 miles with the newer overdrive clutches. What does the MM manual say? How often do you plan on doing it?

Jim, once again the manual gives bad advice...I don't have the car here to go look at the maintenance schedule, but IIRC, it says that the ATF doesn't need changing for something ridiculous like 100,000 miles under normal use, and at (again IIRC) 30,000 for severe duty. I first changed mine when replacing the pan with the factory pan that comes with a drain plug...that was at 15,000 miles...I did it again at 30,000 and, now that I have a blower, I intend to change it every 10,000 miles. I think changing it every 30,000 for a mildly-modded car that isn't driven hard is probably fine.

I agree with you that changing the diff lube at 30,000 may be overkill, but if I'm already under the car for other routine stuff, it's so easy and inexpensive it doesn't make a lot of sense to let it go much longer. Well, that and the fact that I actually ENJOY doing this kind of maintenance... :D

[BillyGman]

When it comes to ring & pinions being destroyed on the Ford 8.8" rear ends like we have in our Marauders, and ring gear bolts coming loose or breaking, I think the two most important requirements are as follows:


#1. The RED (permanent)(#271) LOC-TITE must be used on the ring gear bolts.Many mechanics don't use it on them, and that's bad. If you bring your car to a dealer, or some garage to have the ring & pinion gears changed, chances are, that the place in question will NOT use red LOC-tite on the ring gear bolts unless you supply them with it, and specify that you want them to use it.

#2. The ring gear bolts that come with the new ring & pinion gear set should be used rather than the original factory bolts. Ofcourse setting the bolts to the proper torque spec of 65-77 FT/LBS is also of utmost importance. Hopefully the place that you bring it to uses a torque wrench. I've seen some mechanics who don't. (which is why I do all the mods to my car that I can myself, including gear swaps).

[JimmyXR7]

I agree with you that changing the diff lube at 30,000 may be overkill, but if I'm already under the car for other routine stuff, it's so easy and inexpensive it doesn't make a lot of sense to let it go much longer. Well, that and the fact that I actually ENJOY doing this kind of maintenance... :D[/QUOTE]Jims Reply -
It is also satisfying to me knowing additional (early) fluid changes will extend the life of your cars beyond what others get. However I own 7 Mercurys since I bought the MM last month. Then my wifes Firebird and my Bronco brings the total to 9 cars I need to maintain. So not doing unnecessary maintenance allows me to be able to drive them on the weekends.

Thanks for your advice.

Jim

[TechHeavy]

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Dave, I replied to your e-mail, it bounced, so Ive copied my reply here.

</PRE>




If you refill with Motorcraft 75-140 lube, you'll need to add a 4 oz. bottle of friction modifier, available at any FMC/LM parts counter. A while back, someone here started a rumor that synthetic lube did not require this modifier, but I'm not sure if this is true today. This additive allows the rear end to "slip" properly in hard turns, and without it, you could damage rear end internals. RFOverLord posted great advice. Considering the power on tap with a Trilogy kit, this may be a good time for you to inspect and improve your rear end. He called it a "shinny hinny", but it's really superb reinforcement for the differential. I suggest you open the rear end and inspect internals for wear and tear up to this point. Flush it out, and while it's open, install a Ford Racing/Dana 60 bearing cap stud kit (M-4034-A, $37.95) and rear end girdle (M-4033-G1, $195.00), and I'll tell you why.At 16,500 miles on my Marauder, my rear end came apart. Three ring bolts came apart, one lodged between the ring and the pinion, one went to the bottom of the housing, and the third almost punctured the OEM cover, left an impression looking like a bullet wound. The Richmond 4:10s were done, and the OEM TractionLoc diff destroyed. The repair was over 1500 bucks. I bought an Auburn diff, Ford Racing 4:10s, stud kit, girdle, new axles, new bearings all around, and Motorcraft lube with modifier. 10K miles later, not a hint of a problem, and I am pushing 434 foot pounds of torque into the rear end on a daily basis. I wish I had the chance to take some preventive measures first, they could have saved me 1200 bucks.

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Hi Mac,
Thanks for the heads-up on the email.. I'll fix that right away. Thanks also for all the great info. The parts numbers and prices are very helpful! Also the friction modifier was new info... will do.
I regret your misfortune with the rear end, but I'm gonna take your advice and do the preventative procedures... thanks for helping me gain from your experience.
I'll email you if I have more questions.
Thanks! :rock:
I really hope you make it to MVIII. I think it's up to 3 or 4 beers I owe you now! :D :beer:

[Ron]

[QUOTE=TechHeavy]While getting my oil changed at my favorite 10 minute-type place, I was told that my rear differential fluid was low, and black. They suggested a flush and refill.

I went one time to these "Monkey lubes", years ago.
Do they still VACUUM out the differential fluid ???
Then how do they flush ???

[Mad4Macs]

And how did they know that the rear end fluid looked "black"??? BTW, I use the 80W90 weight. That's fine for me.
<Thread hi-jack mode=on>
BillyG, don't be silly! It was because my rear end fluid WAS ALL OVER MY FRIGGIN' axles, brake pads and wheels!
<rant off, and no, no disrespect to BillyG. Love ya man ;)>
3 transmissions, 2 rear axles, 1 pinion seal and a partridge in a pear tree
<Thread hi-jack mode=off>

[BillyGman]

<THREAD mode="on" hi-jack>
BillyG, don't be silly! It was because my rear end fluid WAS ALL OVER MY FRIGGIN' axles, brake pads and wheels!
<RANT class=inlineimg title=Wink smilieid='\\"5\\"' alt='\\"\\"' border='\\"0\\"' src="images/smilies/wink.gif" <img man ya Love BillyG. to disrespect no no, and off, />>
3 transmissions, 2 rear axles, 1 pinion seal and a partridge in a pear tree
<THREAD mode="off" hi-jack>Uhmm, if there was some kind of joke in there somewhere, then I'm afraid that it got lost over the internet, or I missed it, but my question was for Dave who started this thread. I don't recall him saying that his rear end fluid was all over the place like you say that yours was. All as he sdaid that it was low. he didn't get into detail, and that's why i asked. but no biggie I guess.