Friction modifier is used to keep the clutch packs on a limited slip from chattering. It makes them a bit slipery-er-er. That is a totally different application than using it in a manual tranny.

My uneducated guess would be that that would be a bad thing in a transmission. If it works at all it would not be a cure.

I was wondering when this thread was going to appear! Well , at 800 km I spoke with the dealership service advisor regarding 1st TO 2nd gear grind, and a slight grind into 3rd... this happens when I drive off, after I allow the engine to idle and warm up (5- 10 minutes) I even drove to the dealership and they allowed the car to cool down,I got there at 9am and they did not test drive it till 12 noon.
They told me yes second gear grind is happening and also when you go into third although 3rd was not as bad as sliding into 2nd... service manager looked up on the computer to see if there was any TSB on this, but came empty handed,I suggested that maybe it could be the syncros or a combination of syncros and tranny oil, but they had no answers, at least this complaint is officially logged in with ford.
I was on some other forum, and there was a whole discussion going on about this very subject,so I know Im not the only one experiencing this issue,there were a bunch of members with both 2010 and 2011 gt mustangs discussing this.
Over the holidays, I will be writing a detailed letter to Ford Canada,specifically to the engineering dept requesting a solution to this issue and will be sending this via registered mail.
I dread driving a perfectly NEW 2011 Mustang GT California Special with this issue.I am now at 3900 KM and this issue is still there.
Once the car warms up during driving this issue disappears, but not fully, I see from your post above that this issue has been going on for several years models and am disappointed that FORD has not dealt with it... it's very disconcerting to have this going on a brand new GT!
The grind itself CANNOT be doing any good to the internals and it will progressively keep getting worse. FORD needs to deal with this for it's customers, so far,I am not a happy camper with this ride, and yesterday I received another survey. I made these observations VERY CLEAR in the survey and photo copied the document for my records before I mailed it off, I'll keep you guys posted on this.
On another note: a Merry Christmas to all members

This appears to be a fairly common problem that Ford has not yet stepped up to the plate to fix.

My suggestion is to let Ford know about it and don't let us internet armchair quarter backs have you do anything to jeoparize a claim.

Please keep us posted.

Do not use rp in a tranny. It is meant as a race fluid only and there is alot of info online about how it eats thru gaskets. The oil is the same. What makes it lubricate so well is also what eats at your seals. It is a racing fluids. I have read many threads and independent testing about this stuff. Just because you haven't had an issue doesn't mean you won't. Especially suseptible is anywhere rtv gasket a has been used. Royal purple even warns against using it where rtv has been used as a gasket. Same thing with amsoil syncromesh. Now that I am an amsoil dealer it explains it in the dealers manual. Cork gasket takes longer but will also fall victim to failure. Do what you want but don't say you weren't warned.

I fully agree with you... I am not an engineer, and I am not about to tackle what I really know nothing about, the last thing I want is for FORD telling me that I used a tranny oil that voided my warranty.
A close friend of mine that happens to also be a lawyer has the same issue with a brand new performance white GTCS... basically we bought our Mustangs 3 days apart, his is also a 6 speed the only difference between the two is his came with the 3:55:1 rear end, while mine has the 3:73:1, the rest is identical other than color.
He's beyond pissed, his wife which happens to enjoy driving stick more than auto told him that she is nervous driving "her" new Mustang (he more or less bought it for her) till her tranny gets "fixed" by FORD.
He's talking about a class action law suit against FORD and so far he already has some 20 mustang owner names that are on his band wagon,mine included. He also is looking into canadian automotive arbitration,which will essentially force ford to "BUY BACK" these cars, from what he tells me, an arbitrator's usual judgement in cases such as these is the manufacturer (FORD) will be put on notice to develop a remedy (fix) within 90 days of judgement, failing which they will be ordered to buy back these cars, with full financial restitution to the owners.
I spoke with another close friend of mine that bought a 2011 Mustang Shelby this fall, and they do not seem to have this issue according to him, I also drove his and found shifts are smooth and as expected to "feel" in a brand new car.
I noticed his reverse gear placement is the opposite to where mine is, so maybe it is a different transmission than on the 5.0 GT's.
Man, I've been wanting a Mustang forever and always loved these cars, so I finally buy my dream car and this happens... to be honest with you, I have not mentioned any of this crap to my wife... yet! But she mentioned to me a couple of times what "that grinding noise is" and I told her it's caused by a cold running transmission.
F*ck, I hate to lie to her about stuff like this,but ultimately I'll let her in on this issue if it's not resolved.

Ford has issued a numbers of TSB's for the 2011 Mustang. Hopefully they step up and issue one for this too. It's just the right thing to do.

I know of one TSB for the 2011 mustang regarding the clutch sticking down at high rpm,can you please shed some light on other TSB's for the 2011 Mustang
Maybe we should have a sticky relating to all TSB for the 2011 seeing it's a brand new model with a new engine ( coyote 5.0)
Thanks VAEM

ANY GRINDING in a transmission is never a good thing,and will result in escalated wear and tear on internal components !
FORD needs to address this ASAP... all the advertising in the world regarding "Quality is job #1" is NOT going to convince anyone,in fact if anything they are messing with their integrity. A quality product needs little if any advertising, a satisfied customer is a REPEAT customer,plain and simple. Rushing a new product to market with serious issues punches massive holes in their integrity, and a grinding manual transmission to me is a pretty serious issue,it's not like a bulb burning out or a piece of trim coming off, those would be minor in my books but when it's something of a mechanical nature AND it involves a transmission, then I ask myself, should this company be trusted?

There is a TSB about this problems with the TR3650 and they change the 1/2 and 3/4 sliders with new sycnro. I ve done this TBS a lot in the past years.

There is another TSB to put 3 liter of Mercon V fluid, not more in the TR3650 01-07.

Since Everett is an Amsoil dealer, he can maybe confirm this, but I use Amsoil for the entire drivetrain, and even with Amsoil synthetic in the rear end, they recommend adding 4 oz of Ford Friction Modifier, part # XL-3, but I have never heard anywhere that this is ok to use in a transmission of any kind???

:?