So I had a bad shudder from o/d to a lower gear and was told to use Ford's friction modifier. I couldn't fin th M19546a12 at the dealer so i used the equivalent motorcraft xl-3 and have had no issues what so ever. So now you know. Now my disclaimer is that I am not promising a easy fix for everyone or am I saying this will fix your tranny issues so do blame me if it dont fix your problem.

 

Did You put this in your Trans Or the Rear?

 

Pretty sure he said tranny

 

Yes the trans, ive never thought of it my self. But if you contiplate a min the trans if one big clutch pack like LSD rearend.

 

But is it Compatible with mercon or is it just going to clog the filter?

 

Maybe you don't have a problem doing this but I sure would.
Here is why.
The friction modifier is just what the name says.
It modifies the friction the rear end fluid presents to the clutch paks.
Putting unmodified fluid in a rear with clutch paks will allow the clutches to lock too hard when going around a turn.
In other words the modifier causes the clutch paks to 'slip' a bit by engineered intention. Because of the slip, the paks wear out after just so long.
.
Putting this modifier in a trans to eliminate shudder is going to make the possability of even more slip, just like in the rear.
In place of the shudder you now have more slip and likely shorten the trans life even more.
Putting modifier in covers up an issue that already exists.
It's a case of 'is the glass half full or half empty'.
Away to get more time before rebuild by eliminating the feel and accelerating the trans to it's end. Either way you will have to repair or replace.
.
Shudder is usually an indication that repair is needed.
Shudder is ususally at an engagement point when two surfaces are coming togather. The intermittant 'grabbing' instead of smoothness is what you feel as shudder.
Shudder with a standard transmission clutch engaement is the same thing.
The clutch disc needs replacement and or flywheel face could need resurfacing.
Good luck with it.

 

The only thing ive ever used in my tranny fluid is the Lucas oil trans fix, seems to be good stuff, now i put a quart in just for good measures when i change my fluid

 

Completely understood bluegrass, but to me the aditive is safe for many reasons, 1 being that the trans pulls and shifts fine now, but before it shuddered in and out of o/d. How it was explained to me was that the packs in the tranny slip some aiding in a smoother shift along with varying line pressure.the aditive lets the parts move individually until extreme pressure applied then aditive does the oposite of what its designed to do. Also was told to flush the old fluid out and replace with Chrysler atf because of the similar property it has as friction modifiers in it. All I know is it dont shudder and everything ive read others have said is it last a while for them