LSD Friction Modifiers

[MachinesWithSouls]

Hi guys

Just a quick question as I think about storing the car for the upcoming cold season here in NJ.

Car is a 2011 M3 ZCP 6MT Coupe with about 24,000 miles. It was actually built in April of 2010, making the car over 5 years old. It's had some track days and mountain runs over that time, and though mileage is low, I was planning on changing the transmission and diff fluid before putting it away in November.

Car runs great, no clicking from said diff, but I'm wondering if I need the fluid with or without friction modifiers? Whatever BMW puts in at the 1200 mile service is in there, so if it ain't broke I don't wanna fix it. Simply time to change fluids for fresh stuff.

As always, your help is greatly appreciated!

[dparm]

Originally Posted by SoManyBlueCars

Hi guys

Just a quick question as I think about storing the car for the upcoming cold season here in NJ.

Car is a 2011 M3 ZCP 6MT Coupe with about 24,000 miles. It was actually built in April of 2010, making the car over 5 years old. It's had some track days and mountain runs over that time, and though mileage is low, I was planning on changing the transmission and diff fluid before putting it away in November.

Car runs great, no clicking from said diff, but I'm wondering if I need the fluid with or without friction modifiers? Whatever BMW puts in at the 1200 mile service is in there, so if it ain't broke I don't wanna fix it. Simply time to change fluids for fresh stuff.

As always, your help is greatly appreciated!

Yes, you want it with friction modifiers. BMW has always specified that, and revised the documentation to say "add more FM if the customer complains."

You can always add more FM to suit your taste. Some people are more sensitive to the chatter. My opinion is to use the least amount possible as it will technically decrease LSD locking....so use the FM fluid and see how it is before adding even more.

Are you positive the rear diff fluid wasn't changed? Mine got it at the 30k service, according to the BMW records.

[jphughan]

I will give the opposite opinion. The version with additional friction modifiers is not specified as an acceptable option anywhere outside the U.S. It's also not a product made by Castrol like the regular version, but rather a Castrol product adapted afterward by BMW just for their U.S. customers, and then only the ones who complain. The regular version is still standard even though the cost is very similar. Reading between the lines, I'm thinking BMW may have created this alternate version just for whiny Americans who prize silence above all else and quieted the diff by compromising its actual functionality, which would explain why it's not the standard fill and not even offered elsewhere. Of course I can't prove this, but I specifically asked for the original fill when I had mine changed because even though I have that grinding noise for a while after starting off, it doesn't bother me, and I'd certainly rather have my diff working to the best of its ability than quietly slacking off.

[SenorFunkyPants]

I believe they do offer the Castrol diff oil with extra FM in other regions, at least I was offered it in the UK at the 12,000 mile service after the tech said the diff was a little noisy. I turned it down and have lived with a slight groan with tepid diff oil in tight right hand turns for years (although I don't recall hearing it for quite a while). Now at 60,000 miles the diff still works beautifully.
I would also caution against using the BMW modified oil with extra FM unless you are experiencing significant noise from the diff at fully hot oil temps.

[Helmsman]

Planning to get my diff fluid changed (2011, 23k miles) for the same reason OP, works fine but to get fresh.
Looking at the 1200 mile record it was FM used already at that time (Spring '11) and same goes on the quotation provided for upcoming service. I believe the FM version is what the dealers at least over here have available. Btw noticed it is significantly more expensive then the fluid without.

I don't expect its meaningful to discuss it with tge dealer, as usual.

Cheers

[MachinesWithSouls]

Thanks guys, I'll go with what the car was originally intended for. I've never even heard any clicking. The car makes such a racket at startup anyway, and once underway I can't hear anything over the exhaust, so I'm not worried.

[MachinesWithSouls]

Just to be sure, we're talking about this, correct?

http://www.ecstuning.com/BMW-E92-M3-...ain/ES2602524/

[Rat3d ///M]

I could be wrong, but i think that is the one with the fm in it. I dont think ecs sells the original stuff because ive looked. I also didnt think BMW used Castrol for the diff. I thought they had some OEM branded stuff in a grey bottle with green top.

If anyone can confirm that stuff in the link is the OEM stuff without FM that would be super duper because i am looking at doing this myself in nov before winter storage.

Edit: this is the stuff i was talking about, but this is with FM in it.

http://www.ecstuning.com/BMW-E92-M3-...rain/ES197413/

You can tell the stuff you posted isnt OEM because it says assembled by ECS. if it was OEM it would say genuine bmw. Furthermore, i think the XJ is the code for the FM. the stuff you posted is just an alternate fluid by castrol for our diffs with FM, but definitely not OEM

[MachinesWithSouls]

Originally Posted by ||||||||||

I could be wrong, but i think that is the one with the fm in it. I dont think ecs sells the original stuff because ive looked. I also didnt think BMW used Castrol for the diff. I thought they had some OEM branded stuff in a grey bottle with green top.

If anyone can confirm that stuff in the link is the OEM stuff without FM that would be super duper because i am looking at doing this myself in nov before winter storage.

Edit: this is the stuff i was talking about, but this is with FM in it.

http://www.ecstuning.com/BMW-E92-M3-...rain/ES197413/

You can tell the stuff you posted isnt OEM because it says assembled by ECS. if it was OEM it would say genuine bmw. Furthermore, i think the XJ is the code for the FM. the stuff you posted is just an alternate fluid by castrol for our diffs with FM, but definitely not OEM

I think I had it right. The one you posted has FM in it. BMW fluid is simply Castrol fluid with FM added to it.

Much like our TWS motor oil, the original fill was the Castrol Diff fluid. The assembled by ECS just means they've added whatever gaskets and plugs needed to complete the change. Unless you can't take the clicking, don't use the BMW fluid with FM boosters.

[Helmsman]

This is interesting, appreciate any with actual experience between the fluids to chime in.
I'm thinking maybe I should get the non FM for my service as the dealer doesn't have the stuff...but is the difference possible to notice, even for a drifting fan?

[Flying Ace]

if you can bear the noise, don't use it. The FM technically degrades the function of the LSD.

[Flying Ace]

anyone have the P/N for the non-FM version? My notes says the FM version is:
83 22 2 282 583

[thekurgan]

I've never used the FM modified stuff BMW has offered. IIRC, the only time the fm is actually present is during the initial 1200 mile break in, probably to avoid the heat build up during that time. Groaning diffs are normal, chatter isn't. Too many M owners complain about groaning, so they put this FM boosted shit out there for that noise; but it does lessen the diff ability to do its job. By the same token, those that complain about the groan, for the most part, aren't using the car in the manner intended.

[dparm]

Originally Posted by Flying Ace

anyone have the P/N for the non-FM version? My notes says the FM version is:
83 22 2 282 583

Castrol does not produce Syntrax 75w140 (formerly known as SAF-XJ) without the limited slip additive, from what I can see. You'll have to go to a different brand.

Anecdotal evidence shows that the non-BMW branded Castrol Syntrax has less of the FM. BMW's version has extra FM added, per the front label saying "+FM Additive".

If you want Syntrax with the lower amount of FM, Mercedes part 001989520310 is just that. ECS Tuning sells it, or grab it from a local MB dealer. It's what came in your rear diff from the factory.

[Flying Ace]

Originally Posted by dparm

Castrol does not produce Syntrax 75w140 (formerly known as SAF-XJ) without the limited slip additive, from what I can see. You'll have to go to a different brand.

Anecdotal evidence shows that the non-BMW branded Castrol Syntrax has less of the FM. BMW's version has extra FM added, per the front label saying "+FM Additive".

If you want Syntrax with the lower amount of FM, Mercedes part 001989520310 is just that. ECS Tuning sells it, or grab it from a local MB dealer. It's what came in your rear diff from the factory.

thanks for the info, is it this?

http://www.ecstuning.com/BMW-E92-M3-...ain/ES2602524/

[dparm]

Originally Posted by Flying Ace

thanks for the info, is it this?

http://www.ecstuning.com/BMW-E92-M3-...ain/ES2602524/

Yes, that appears to be the "lower FM" version (aka the factory fill).

There are plenty of other alternatives out there. Don't feel compelled to use the Castrol fluid, though it is a pretty good one.

[SenorFunkyPants]

Just to confirm...Castrol SAF-XJ has always contained friction modifiers and was the OEM fill for E9x M3s. Unless you have a particular reason for wanting some other oil then SAF-XJ is the oil I would go with (or whatever it has been renamed to).

[dparm]

Originally Posted by SenorFunkyPants

Just to confirm...Castrol SAF-XJ has always contained friction modifiers and was the OEM fill for E9x M3s. Unless you have a particular reason for wanting some other oil then SAF-XJ is the oil I would go with (or whatever it has been renamed to).

Correct, SAF-XJ (now called Syntrax Limited Slip) has always had the friction modifiers and was the factory fill.

BMW's version of it simply has additional friction modifiers that were added due to customer complains of noisy differentials.

I think the safest approach is to use the factory fill stuff and see how you like it. If the noise bothers you, buy a bottle of FM and add until the noise goes away.

[thekurgan]

The Redline 75w140 NS lacks any type of friction modifier. It's what I've used for years.

http://www.redlineoil.com/product.aspx?pid=39&pcid=4