is this fluid safe for e9x m3?

[Hawkaj]

had some laying around from a few years ago and never used it

[fs34]

Your diff will be noisy with that, assuming it doesn’t have friction modifier like the OE fluid.

[Scharbag]

Originally Posted by fs34

Your diff will be noisy with that, assuming it doesn’t have friction modifier like the OE fluid.

This fluid does have friction modifiers in it. I run that fluid in my diff and it works great.

The 75w140NS version does not have modifiers. And the bottle looks very similar 🤦*♂️

Cheers,

[Hawkaj]

Originally Posted by Scharbag

This fluid does have friction modifiers in it. I run that fluid in my diff and it works great.

The 75w140NS version does not have modifiers. And the bottle looks very similar *

Cheers,

its working great so far, no noise

[nrubenstein]

Originally Posted by Scharbag

This fluid does have friction modifiers in it. I run that fluid in my diff and it works great.

The 75w140NS version does not have modifiers. And the bottle looks very similar 🤦*♂️

Cheers,

Well. Nitpicking, but it is unlikely that it has friction modifiers to the same level as the OE fluid. One should expect to need additional modifier in order to limit / eliminate low speed scrubbing in turns.

I'm personally not a huge fan of Redline in general. I've just never been happier with an RL product vs. others.

[decimation1]

Does this "scrubbing" sound like tires rubbing? I've got a sound like this hard right, super low speed, like parking lots.

[ATLIEN]

Originally Posted by decimation1

Does this "scrubbing" sound like tires rubbing? I've got a sound like this hard right, super low speed, like parking lots.

Curious to know more about the scrubbing sound. Is that at certain rpm or just when turning, etc?

[nrubenstein]

The scrubbing sound is the diff clutches engaging and causing the inside tire to try to skip. You should only hear it when turning very sharply at low speeds. Added friction modifier should make it go away. Do NOT add a lot. Add a little at a time.

Friction modifier makes the diff engage a bit less. Too much modifier, and the diff is too open. Too little, and you get scrubbing and maybe extra clutch wear.

[decimation1]

Originally Posted by ATLIEN

Curious to know more about the scrubbing sound. Is that at certain rpm or just when turning, etc?

It's just turning at a very low speed RPM makes no difference, like pulling out of my driveway, hard right and uphill.

[decimation1]

Originally Posted by nrubenstein

The scrubbing sound is the diff clutches engaging and causing the inside tire to try to skip. You should only hear it when turning very sharply at low speeds. Added friction modifier should make it go away. Do NOT add a lot. Add a little at a time.

Friction modifier makes the diff engage a bit less. Too much modifier, and the diff is too open. Too little, and you get scrubbing and maybe extra clutch wear.

Excellent information, so how much is "a little at a time"? I had my diff fluid changed about a year ago and sadly put very few miles on the M3 since then and it didn't make the sound beforehand, all makes sense now as it wasn't OEM fluid.

[nrubenstein]

Originally Posted by decimation1

Excellent information, so how much is "a little at a time"? I had my diff fluid changed about a year ago and sadly put very few miles on the M3 since then and it didn't make the sound beforehand, all makes sense now as it wasn't OEM fluid.

Redline says to add an ounce at a time.

[decimation1]

Originally Posted by nrubenstein

Redline says to add an ounce at a time.

Thanks!!

[Scharbag]

Originally Posted by nrubenstein

Well. Nitpicking, but it is unlikely that it has friction modifiers to the same level as the OE fluid. One should expect to need additional modifier in order to limit / eliminate low speed scrubbing in turns.

I'm personally not a huge fan of Redline in general. I've just never been happier with an RL product vs. others.

I have run RL 75w140 for a while now and no issues. I have also used the Castrol SAF-XJ with the same results.

I just cannot accept that the BMW fluid is $90 per 500ml... Never ever will I pay that much for diff oil. I get a deal on Red Line so that is what I use.

Cheers,

[nrubenstein]

Originally Posted by Scharbag

I have run RL 75w140 for a while now and no issues. I have also used the Castrol SAF-XJ with the same results.

I just cannot accept that the BMW fluid is $90 per 500ml... Never ever will I pay that much for diff oil. I get a deal on Red Line so that is what I use.

Cheers,

I prefer Motul (what I have in the E90), or in many cases Mobil1.

Years ago, Bob Tunnell compared RL to M1 in his built conepacking diff, and found 20 degrees LOWER temperatures with the M1.

I've bought many cases of Redline. It's generally fine, although I have hated it in every transmission that I've tried it in.

[Scharbag]

Originally Posted by nrubenstein

I prefer Motul (what I have in the E90), or in many cases Mobil1.

Years ago, Bob Tunnell compared RL to M1 in his built conepacking diff, and found 20 degrees LOWER temperatures with the M1.

I've bought many cases of Redline. It's generally fine, although I have hated it in every transmission that I've tried it in.

Oooof - 1L of Motul 75w140 seems to list for $158CAD... Is it a mixture of unicorn tears and angel piss? Woza...

Cheers,

[nrubenstein]

Originally Posted by Scharbag

Oooof - 1L of Motul 75w140 seems to list for $158CAD... Is it a mixture of unicorn tears and angel piss? Woza...

Cheers,

Being in Canada is rough. It's $25-30/L in the US. Even adjusting for the weak CAD...

[MikeHawk7]

For what it's worth, I'm going to be putting in Amsoil Severe Gear 75W-140 when I find the time. I'll let you know how that goes and if it'll need additional friction modifier.

[vm]

Originally Posted by decimation1

Excellent information, so how much is "a little at a time"? I had my diff fluid changed about a year ago and sadly put very few miles on the M3 since then and it didn't make the sound beforehand, all makes sense now as it wasn't OEM fluid.

Just FYI, the diff in these cars are viscous type not clutch type so any chatter is not related to clutches.

[nrubenstein]

Originally Posted by vm

Just FYI, the diff in these cars are viscous type not clutch type so any chatter is not related to clutches.

This is wrong.

It's a weird hybrid of viscous and clutch. There absolutely are clutches in there.

[vm]

Originally Posted by nrubenstein

This is wrong.

It's a weird hybrid of viscous and clutch. There absolutely are clutches in there.

You're right. I should have been more detailed. There are clutches in there that do the LSD action, However, these clutches are sealed and use a silicone oil for their action which doesn't come into contact with the gear oil. My point was that the gear oil that you use will have no effect on the LSD behavior of this type of differential and should have no effect on clutch chattering as is doesn't reach the clutches.

[nrubenstein]

Originally Posted by vm

You're right. I should have been more detailed. There are clutches in there that do the LSD action, However, these clutches are sealed and use a silicone oil for their action which doesn't come into contact with the gear oil. My point was that the gear oil that you use will have no effect on the LSD behavior of this type of differential and should have no effect on clutch chattering as is doesn't reach the clutches.

If that were true, then why does BMW sell friction modifier fluid for the M-Variable diffs?

A sealed viscous diff has no different lubrication requirements from an open diff. The E46 M3 (which has the same style of diff) was what they developed the current style of fluid for, the purpose of which was to solve clutch noises.

(We actually have true viscous diffs in my wife's 325iX. Both the transfer case and the rear diff are viscous couplings.)

Edit: And more to the point, why did adding a couple ounces of friction modifier make my clutch chatter go away if it's a totally sealed unit?

I don't see how you even could seal the clutches into the viscous coupling. Clutch debris would destroy it very, very, very rapidly.

[Helmsman]

The diff should make some noise when turning at low speed, sign of function imo. Go easy with the "friction modifier".