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

[01SG]

Counterpoint: Given the importance of the differential and the infrequency of changing the fluid, it is worth skipping the hassle and getting the factory stuff that is already measured perfectly.

You will indeed need three bottles. It takes about 1.2 liters.

https://www.fcpeuro.com/products/bmw-motorsport-rear-differential-fluid-5-liters-83222282583?ads_cmpid=352576039&ads_adid=22972407319&ads_matchtype=&ads_network=g&ads_creative=85218275839&utm_term=&ads_targetid=aud-667196784149:pla-327620319311&utm_campaign=&utm_source=adwords&utm_medium=ppc&ttv=2&gclid=EAIaIQobChMIoZbg0ZW6-AIVex-tBh3FqQ-2EAQYASABEgJDUPD_BwE

[COVID-19]

I followed this.

https://youtu.be/lUpOFxGtN-E

[eacmen]

I followed this.

https://youtu.be/lUpOFxGtN-E

Only reason I didn’t follow this was there was only anecdotal evidence that this combination yielded the bmw factory formula.

Since the castrol by itself is made for LSD there has to be some FM in it already. And as we know Castrol is known to change formulas over time without changing product labels (i.e. 10W-60 TWS is not the same formula as Edge Supercar but compatible)

I don’t think you can go wrong either way. Plenty of folks just run Redline with no FM and haven’t blown their diff up. If you ask Bimmerworld they recommend straight Redline with no FM (would not recommend).

The oil I took out was pink/purple - not sure what the fuck it was but it groaned alot in slow speed full lock. The straight Castrol Syntrax is quiet.

[pawelgawel]

Thank you ALL gents, i was worried my diff was coming out until I began reading up on this issue...

[bigjae46]

Counterpoint: Given the importance of the differential and the infrequency of changing the fluid, it is worth skipping the hassle and getting the factory stuff that is already measured perfectly.

Agreed for a street car.

Different for a track car that changes the fluid more often. The fluid takes a lot more heat and wear so it needs to be changed a lot more frequently. Keep in mind more FM results in less lock up which might not always be a bad thing.

[jet_dogg]

Counterpoint: Given the importance of the differential and the infrequency of changing the fluid, it is worth skipping the hassle and getting the factory stuff that is already measured perfectly.

You will indeed need three bottles. It takes about 1.2 liters.

https://www.fcpeuro.com/products/bmw...SABEgJDUPD_BwE

That would be too easy.

Remember, people like to struggle.

[Tbonem3]

Lest we forget, E46 M3s only came in to get the FM booster if the owner complained about noise. The SAF XJ is already a LSD specific fluid. I'd rather have some noise, and solid lock up than no noise and more slip, as I've said in previous diff fluid related threads.

[Casa de Mesa]

Lest we forget, E46 M3s only came in to get the FM booster if the owner complained about noise. The SAF XJ is already a LSD specific fluid. I'd rather have some noise, and solid lock up than no noise and more slip, as I've said in previous diff fluid related threads.

+1

I haven't run FM for 45k miles. No noise, no chatter, no I'll side affects. While I used FM before, I haven't on this diff.

Granted, I have changed the fluid 3 times in those 45k miles for various reason, but the fluid is always cleaner than I expect.

[fattycharged]

I don't really understand why the groan bothers people.

[jpiazzam3]

I followed this.

https://youtu.be/lUpOFxGtN-E

I followed this as well. I bought the friction modifier from a local ford dealer for 8$. And I used a cooking syringe to measure it out. So far so good


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[bavarian3]

Only reason I didn’t follow this was there was only anecdotal evidence that this combination yielded the bmw factory formula.

Since the castrol by itself is made for LSD there has to be some FM in it already. And as we know Castrol is known to change formulas over time without changing product labels (i.e. 10W-60 TWS is not the same formula as Edge Supercar but compatible)

I don’t think you can go wrong either way. Plenty of folks just run Redline with no FM and haven’t blown their diff up. If you ask Bimmerworld they recommend straight Redline with no FM (would not recommend).

The oil I took out was pink/purple - not sure what the fuck it was but it groaned alot in slow speed full lock. The straight Castrol Syntrax is quiet.

How is it now that it's been a while?

Do you have a source that suggests this stuff has FM in it? I just put this in my diff and am now discovering all this nonsense.

I sorta just trusted FCP since they had it and they typically weed out the stuff that isn't quality, but now it's actually not available anymore.

[eacmen]

How is it now that it's been a while?

Do you have a source that suggests this stuff has FM in it? I just put this in my diff and am now discovering all this nonsense.

I sorta just trusted FCP since they had it and they typically weed out the stuff that isn't quality, but now it's actually not available anymore.

Works great for me.

[bavarian3]

Works great for me.

Glad to hear. I'll give it a shot since it's already in there. 😂

[Slideways]

Something to note, BMW sells the same Castrol SAF-XJ diff oil without FM modifier for the F80 M3 - P/N 83222357992 (1L = $38)

The E46/E9XM stuff specifically states SAJ-FX + FM booster with P/N - 83222282583 (0.5L = $46)

The + FM booster is quite a bit more.

[Cronenberged]

I used Amsoil diff oil and I've not had issues. I don't have a rear interior or sound deadening and my diffs quiet.