2 Different Friction Modifiers???

[BillyGman]

Does anyone know if there are two different Friction Modifier additives made by Ford for the Marauder rear end? I ordered one 4 ounce bottle of the stuff from Summit Racing, and it's different than the one I picked up at the Ford Dealer. It says "XL-3" on the bottle from the dealer, and is a light tan color just like a thin oil. it says "Motorcraft" on it. But the one I got from Summit is a blue colored subtance that has a real strong scent to it that can be smlled w/out even opening the bottle, and instead of saying "Motorcraft" on it, it says "Ford Motor sports" and the number on it is M-19546-A So these appear to be two different products to me. Which one should be used for the Ford 8.8" rear?

[joflewbyu2]

i got the m-19546-a ford motorsports one with my SVO rear cover girdle and stud kit.

[Ross]

This is news to me. Are there additives like this which are really good for different parts of the car? Awhile back I started a thread asking about different engine additives, and after overwhelming response against any additives, I went with the majority and didn't add anything. But are there other areas (fuel additives, tranny , rear end ) which have additives which really do some good?

[TripleTransAm]

For those who may be wondering, the Diff oil Friction Modifier "additive" isn't an "additive" per se. When most folks say "additive" they immediately think of some product that MAY be added to some lubricant or automotive fluid to enhance its operation. This is not the case with the diff fluid additive.

The additive is necessary because it modifies the friction coefficient of the limited-slip clutches. The clutches attempt to keep both axles rotating at the same speed. This is not what you want happening on turns, where one axle HAS to rotate faster than the other. So if the clutches were too 'grabby' the diff would emit a serious clunking sound as the clutches caught/slipped/caught/slipped/caught/etc.etc. due to the different rotating speeds. Excessive clutch wear would also occur. So the friction modifier allows the clutches to slip more smoothly, and yet allows them to grab nicely when both axles are rotating at the same speed. You will be able to turn corners with the clutches slipping smoothly instead of grabbing violently.

Unfortunately, I do not know why there would be two different Ford additives.

[Ross]

TTA, thanks for the 411. So is this something that we should all be using? If so, I'm off to the dealer to get some.

[TAF]

Originally posted by Ross
So is this something that we should all be using?

I don't use it...I've debated it with several here (off-line)...but, the guy who is the ONLY guy that I'll let touch my car said not to.
So it is NOT mandatory, however for most it is recommended.

[Zack]

You should use the friction modifier or you are asking for trouble. I remember the Posi Rear End in my 76 Cadillac had a metal tag on the diff cover stating it was Mandatory to use it. In case anyone didnt know this, friction modifier is in our Diff from the factory- use it and like it.

[martyo]

It's in my car......

[chrtra1]

In any Ford trac-loc rear end you MUST use the approprate friction modifier. This is NOT optional.

[TAF]

I know, I know...I've heard it. Going to be doing a check on the gears next week. I'll report back any unusal developments without it.

[TripleTransAm]

Originally posted by TAF
I don't use it...I've debated it with several here (off-line)...but, the guy who is the ONLY guy that I'll let touch my car said not to.
So it is NOT mandatory, however for most it is recommended.


Have you had your diff oil changed? If not, then you ARE using it... it's a mandatory part of the diff oil "package" and comes from the factory that way.

Honestly, it's the first time I've ever heard of anyone recommending NOT to include the friction modifier, UNLESS you're using an aftermarket synthetic that already contains some clutch friction modifiers. Even those synthetic gear lubes provided by the auto manufacturers (such as GM's sythetic 75W90 diff oil) require the additive so it's not a matter of synthetic = no additive. The Panther shop manual states that 4 oz. of the stuff is required along with their 80W90 rear axle lube (which suspiciously does not sound like a synthetic lube to begin with).

With regards to the 2 different parts numbers, the shop manual says XL-3. Maybe the other part number is a racing spec?

Too bad I just changed my WS6's diff fluid on Monday, otherwise I could have taped what a clutch-clunking diff sounds like. The car had a tendency to 'wear out' the modifier and I've had to change the diff oil every two years, as it would be clunking within 12-24 months of use. Turns out the techs that did the previous fills didn't put enough of the additive in there, as evidenced by the excessive amount remaining in the used bottles they left for me. So this time I did it myself, and made sure the right quantity of additive was used. Got my fingers crossed...

[TAF]

I've got Ford Racing full-syn fluid in there from the gear change. And, yes...you can feel the posi/clutch working. Many told me to change a couple said no prob. We'll see when we brake her open next week.

[TripleTransAm]

Originally posted by TAF
I know, I know...I've heard it. Going to be doing a check on the gears next week. I'll report back any unusal developments without it.


You won't find any evidence of wear on the gears, it has no bearing (no pun intended) on gear wear. It's the clutches that will excessively shred themselves over time instead of smoothly letting go everytime you turn. I've never seen the inside of the MM's diff, but if it's anything like the General Motors 10 bolt in my WS6, you won't be able to easily detect clutch wear.

What I DID notice this time around, after driving with the clunking rear for about a year or so, was what I would consider an excessive amount of metallic-like clutch dust (I hope it was clutch dust) on the rear cover magnet. If it is clutch dust, then I'm going to pay doubly close attention to any future clutch-related clunking that may occur.

FWIW, I bought my GTA with a clunking diff, most pronounced when I backed up slowly while turning. A diff oil change (+ additive) cured that, back in 1994. It hasn't clunked one bit since then, close to ten years later.

[TripleTransAm]

Originally posted by TAF
I've got Ford Racing full-syn fluid in there from the gear change. And, yes...you can feel the posi/clutch working.


The way I see it, the fact you can feel them grabbing means they're not letting go smoothly, hence the need for the additive. I'm not really sure that NOT having the additive in there contributes to any positive result... any way you look at it, it's causing the following:

1) the clutches are rubbing against each other too hard, and will probably wear each other's surface material quicker

2) you're probably soaking up more driveline power because the clutches are having a harder time letting go. That results in a parasitic drag on the driveshaft (since most likely you will NOT be dragging the outside tire around a curve).

Anyway, that's pretty much all I can say about the issue. Considering the spring force on most posi units, it's almost impossible to visually detect clutch wear until they're about to let go, so this discussion could go on for many many many miles. Best to stick to what you feel most comfortable with. (and if the Ford synth rear fluid does include the job of the modifier, so be it... I'll keep it in mind when I get to the situation of changing my MM's diff fluid).

[jgc61sr2002]

Triple TA - Thanks for the info. You have to add friction modifer only when you change the rear end oil.

[chrtra1]

(and if the Ford synth rear fluid does include the job of the modifier, so be it... I'll keep it in mind when I get to the situation of changing my MM's diff fluid). [/B]

The Ford synthetic axle lube does not contain any modifier. Modifier still needs to be added seperately.

[BillyGman]

that TripleTA is correct. I called it an "Additive" but that's not to say that it's some type of after market, or vendor product that's optional. It IS in the MM rear end from the factory, and the only time that you have to add more is if you drain the gear oil from the rear end in the event of a simple change, or when you're doing any work to it such as changing the gears like I am about to do. I call it an "additive" simply because it comes in a seperate bottle than the gear oil does, and it has to be "Added" to the gear oil. But again, that doesn't mean that it's optional. It's mandatory. There's good reason why Ford calls out for this. And TTA has explained that.
But I still think that there are two different Friction Modifiers from Ford, because not only are the two different in color(one is blue, and the other tan) but they have different part numbers, and only the blue stuff has a distinctive and overly strong odor to it. So much so that if you simply leave it in a room of your house even though you haven't even opened the bottle, then in a couple hours that entire room has a burnt plastic type smell to it that is very noticeable as soon as you enter it. But even though these are two different products, maybe they are interchangeable or equivalent. I don't really know for sure though. But the bottom line is that you need one of these, they are made by Ford, and the stuff is sold at the Ford and Mercury dealers specifically for Ford rear ends like the one in the Marauder.

[Ross]

Lots of good info here on a subject I had never even heard of before. So if I understand, since I still have the original rear end lubricant in my car, it should have come from the factory with this stuff already there, and I shouldn't have to worry about anything until it's time to chance the rear end oil, right? I just hope the guy at the factory was doing his job and added it when he was supposed to!

One question though. Does it make any difference if you have the 300A or B, and either you have or don't have traction control? Do both need this stuff?

Oops, one more question. Regardless of factory guidelines, when do all of you suggest changing the rear end oil, assuming you are not changing the gears and have to do it anyway?

[BillyGman]

shouldn't have to be changed for several years. And weather or not your car has traction control has nothing to do w/the need or the the presence of the friction modifier additive. The additive is simply neccessary if you have a "Locking" rear end in your car(which is what GM calls a posi-traction, or "Posi" rear end on their cars. Ford doesn't use that term, but it's the same thing).

[frdwrnch]

Friction modifier is necessary in Ford limited slip differrentials. YES THERE ARE TWO KINDS OF MODIFIER! The new modifier has low odor and is the replacement for the old shark liver oil based modifier. I believe the old stinky stuff (from Ford) is more effective but have not had any luck finding it through Ford Parts. They followed up on it and said this is the replacement. Probably had some hazardous materials in it so they "modified" it. PURE FORD MAGIC!

[Dr Caleb]

Originally posted by Ross

One question though. Does it make any difference if you have the 300A or B, and either you have or don't have traction control? Do both need this stuff?

Oops, one more question. Regardless of factory guidelines, when do all of you suggest changing the rear end oil, assuming you are not changing the gears and have to do it anyway?

First answer. No. All MM's have 'track-loc' or 'limited slip' rear ends. "Traction Control" is a function of the anti-lock brakes and the ECM computer. It has nothing to do with the rear end.

Second: Some books will tell you 'never'. In my Crown Vic, when using 80W-90 oil, the oil doesn't need to be changed. I don't have my MM book with me, but I'll check it later - it may say something similar.

But I ignore the book. I change the oil in my CV rear end yearly. Not because I need to, but because I like to open it up check that there are no bits of metal etc in there, and put on new gaskets. I also use 75W-90 full synthetic oil in the rear end.

[BillyGman]

Originally posted by frdwrnch
Friction modifier is necessary in Ford limited slip differrentials. YES THERE ARE TWO KINDS OF MODIFIER! The new modifier has low odor and is the replacement for the old shark liver oil based modifier. I believe the old stinky stuff (from Ford) is more effective but have not had any luck finding it through Ford Parts.

I have both Modifiers. Summit Racing sells the Ford Motorsport stuff. That's the blue stuff that smells a lot.
So which would you guys use if you had both(perhaps it really doesn't matter though).....

[rauder775]

Perhaps I did not look close enough, but I did not see an interval (mileage) when posi/axle fluid should be changed. When do you suggest?

[thePunisher]

the 2 different modifiers ford makes are xl-3 and xl-7

[BillyGman]

Perhaps I did not look close enough, but I did not see an interval (mileage) when posi/axle fluid should be changed. When do you suggest?Wow you sure dug up a seriously old thread. :eek: But to answer your question, the Ford service manual says to change the rear end fluid at 75,000 miles.

[Marauderjack]

The "Stinky" one works the best!!! :beer: :burnout:

Ford went to a less fragrant one a couple of years ago but evidently had problems so the smelly one is back!! :bows: My local dealer has it and I think it is about $5.00 a bottle.

Marauderjack :D

[Bradley G]

Ditto on the stinky one! The lube that is.:P PEEEE EEEEWWWWW!!!

[fastblackmerc]

Ditto on the stinky one! The lube that is.:P PEEEE EEEEWWWWW!!!
When I had my 4.10's installed used Redline synthetic lube, was told you don't need the additive and have no problems for 10,000+ miles.

[metroplex]

I too noticed this... AFAIK the green/blue stuff is XL-3 as well but labeled under the FMS/FRPP line.

I wouldn't be surprised if they just added the blue dye to make it more "Ford"ish.

I have a few bottles of the XL-3 and decided to use the FRPP FM that came with the clutch rebuild kit (blue/green).

I used 3 qt of Redline + the FM for my 8 clutch setup.

Friction Modifier's purpose is to reduce friction. FM breaks down over time when exposed to high temperatures. This is the reason you get TC shudder (TC is programmed for steady state slip at certain speeds) and why you need to change the ATF.

If you're not hearing a groaning noise when making turns, you're OK.

[ahess77]

When I had my 4.10's installed used Redline synthetic lube, was told you don't need the additive and have no problems for 10,000+ miles.

Ditto on what he did. NO problems yet, I didn't add anything to the Redline with the friction modifier already included.

[BillyGman]

Ditto on what he did. NO problems yet, I didn't add anything to the Redline with the friction modifier already included.Not to change the subject, but I just noticed in your post sig that your Marauder was stolen, and then recovered nine days later? How was it at the time of recovery? Any major damage?

[metroplex]

Not to change the subject, but I just noticed in your post sig that your Marauder was stolen, and then recovered nine days later? How was it at the time of recovery? Any major damage? That would be known as the NJ/NY/CT tri-state test drive special. it happened to our 1981 T-bird back in 82 or 83.

[ahess77]

Not to change the subject, but I just noticed in your post sig that your Marauder was stolen, and then recovered nine days later? How was it at the time of recovery? Any major damage?

http://www.mercurymarauder.com/forums/showthread.php?t=13842&highlight=ahess77

Got it back, dealer took care of damages. It doesn't seem any worse off for the time spent away.

[Krytin]

I have both Modifiers. Summit Racing sells the Ford Motorsport stuff. That's the blue stuff that smells a lot.
So which would you guys use if you had both(perhaps it really doesn't matter though).....Billy,
Use the dark blue "smelly" stuff - it is the stuff I use when rebuilding the rears in the work trucks. F-350's & 450's w/FoMoCo clutch type posi's & no problems! It's a hard smell to get off once you get it on you!

[BillyGman]

Billy,
Use the dark blue "smelly" stuff - it is the stuff I use when rebuilding the rears in the work trucks. F-350's & 450's w/FoMoCo clutch type posi's & no problems! It's a hard smell to get off once you get it on you!Thanks for the info, but since this thread is so old, I gotta tell you that I performed the gear change a long time ago, and I used the tan looking stuff (not the smelly one). But I'll keep what you said in mind for future reference. ;)

[Skiordie53]

at whit melage are you guys changing the rear end fluid. i am just shy of 35k now.

[BillyGman]

at whit melage are you guys changing the rear end fluid. i am just shy of 35k now.It states in the Ford manual that it should be done at 75,000 miles. I changed mine at 1,500 miles, and then again at 4,000 miles, but only because of the two gear changes that I performed (the first one being the 4.10's, and then the second being the 4.56's). But in your case, unless you're going to perform a gear change, then I wouldn't worry about changing the fluid until atleast the 50,000 mile mark.

[Marauderjack]

Pull the magnetic fill plug and see if there is any metal other than fine "Graphite" looking stuff which is normal!! :beer:

Check level of gear oil and add if low.....then you are good to go!! :bows:

I have changed mine on most cars every 50K miles and only had axle trouble on a 2000 CV but It had almost 200K miles on it and had been a superb car!! :banana2: When I pulled the magnetic plug I knew I had problems since it looked like a bird wing it had so much metal on it....Also had a pretty good roaring noise in the rear!! :mad:

Marauderjack :D

PS: As stated before the "Smelly" FM will stink up....you....your car....your garage...your house and it takes awhile to go away!!! BE CAREFUL NOT TO SPILL IT!! :help: