wtf.... Diff OIL, can't find a FM Booster

[pawelgawel]

Hi guys,
I used LMoly for my diff and I have the grind at a slow pace turn, so I want to switch to OE/OEM oil (Castrol) and add some FM Booster.. Apparently this oil is like gold these days, can't find it anywhere and BMW oil locally is $75/.5L (CND) which is NOT FUNNY. Where can i get the FM Booster separately? I can get the old BMW oil without the FM booster for about $40 USD/L which is much cheaper.

[Casa de Mesa]

https://www.fcpeuro.com/products/limited-slip-friction-modifier-4oz-80301

[pawelgawel]

https://www.fcpeuro.com/products/lim...fier-4oz-80301

thank you!
from what Ive gathered, i need about 4.6% of FM in the diff, so roughly about 10-11ml which would be this one bottle.

Im hoping to find something locally in canada and add it to my LM fluid to see if that helps... but might just order the fluids from fcp

[Casa de Mesa]

Got it. Look for Red Line or Motorcraft FM locally. They are both pretty readily available in the lower 48 and would think they are for our neighbors up north.

I have used both of these.

[pawelgawel]

sweet, thanks for the info!

[eacmen]

I just swapped diff fluid. Previous owner I think had either Redline or Royal Purple in there. The diff used to groan when doing low speed figure 8. I used the Castrol Syntrax with FM in it and the groan is totally gone:

https://www.fcpeuro.com/products/syntrax-limited-slip-differential-fluid-castrol-1543c9

It already has FM in it. $20/.5ml. Its a merc part they send you so might be available locally at merc dealership for less.

[jet_dogg]

It would be interesting to see how and if lock-up is affected by friction modifiers. Did you notice anything different after the switch?

[pawelgawel]

I just swapped diff fluid. Previous owner I think had either Redline or Royal Purple in there. The diff used to groan when doing low speed figure 8. I used the Castrol Syntrax with FM in it and the groan is totally gone:

https://www.fcpeuro.com/products/syntrax-limited-slip-differential-fluid-castrol-1543c9

It already has FM in it. $20/.5ml. Its a merc part they send you so might be available locally at merc dealership for less.

I was under the impression this Castrol is Castrol SAF-XJ, without the FM Booster... I was going to use this and still add the FM booster

[pawelgawel]

do we need 3L or 1.5L?

[eacmen]

I was under the impression this Castrol is Castrol SAF-XJ, without the FM Booster... I was going to use this and still add the FM booster

It has FM in it. Some claim it’s not enough, not the right type, etc.

I just put it in so not sure how it works yet. But so far much better than what was in there!

I used a little less than 1.5L.

[pawelgawel]

It has FM in it. Some claim it’s not enough, not the right type, etc.

I just put it in so not sure how it works yet. But so far much better than what was in there!

I used a little less than 1.5L.

much appreciated.. somewhere I read we need 3 quarts, which is almost 3L, thought that sounded too much. Im also cusrious if anyone added the FM booster to other oils with success of getting rid of that grind. Im a fan boy of LM, so Im a little disappointed with the results.

[eacmen]

much appreciated.. somewhere I read we need 3 quarts, which is almost 3L, thought that sounded too much. Im also cusrious if anyone added the FM booster to other oils with success of getting rid of that grind. Im a fan boy of LM, so Im a little disappointed with the results.

If you trust this dude’s research into FM ratio:

https://youtu.be/lUpOFxGtN-E

[pawelgawel]

Ok, so I should be adding the FM to the Castrol bottles. Thats how I understood other posts

[eacmen]

Ok, so I should be adding the FM to the Castrol bottles. Thats how I understood other posts

My perspective is when using diff fluid that is already engineered for LSD then adding FM is personal preference. If you’re getting groaning from the rear in slow figure 8s then add FM.

[FBloggs]

I believe that Your local Ford dealer sells FM.