Diff and transmission change for track, how often

[TheMechanic]

Hi all,

I have about 2 years and maybe 8 - 10 track days on my transmission oil, and about the same on the diff... how often you guys change these?

I had the redline with no slip additive - on diff - and it became very noisy on tight turns, so i just put in the BMW one with slip stuff, and it's all quiet now. I do have a slight whine in 4th gear around 50mph...when just cruising (not under load) barely audible, but this is since I owned the car, never got louder, I think it's ok ?

Thanks for any feedback

[e92BMW///M3]

I just changed mine also but interested the intervals others follow

[TboneS54]

You might want to go back to a diff lube that doesn't have any friction modifier or just a little bit, so that there's not too much slip. Ya the diff is quiet, but you may not be putting down as much power through a turn?

Modern synth lubes are very impressive. I wouldn't change them out sooner than regular intervals unless this were a truly dedicated race car, competing, piloted by an intermediate or expert level driver. Not a typical enthusiast m3 visiting a practice day at a track a few times a year.

[amg6975]

I do mine every couple years. Probably something like 50-60 track days. Always looks brand new, Blackstone always says it could go way longer.

Also run the Redline NS fluid and yeah it groans but oh well.

[omgzirra_exe]

i hear 30k is a good interval for a street car, a track car probably much sooner, on a built diff maybe annual... depending on events per year or mileage based?

[Ximian]

I do it about every year with Liqui Moly fluid. No noise or issues.

[TheMechanic]

Originally Posted by TboneS54

You might want to go back to a diff lube that doesn't have any friction modifier or just a little bit, so that there's not too much slip. Ya the diff is quiet, but you may not be putting down as much power through a turn?

Modern synth lubes are very impressive. I wouldn't change them out sooner than regular intervals unless this were a truly dedicated race car, competing, piloted by an intermediate or expert level driver. Not a typical enthusiast m3 visiting a practice day at a track a few times a year.

Is that a possibility, to lose power in turns? I know the slip additive allows more slip to eliminate chatter, but we're not talking about losing HP due to it ?

[omgzirra_exe]

Originally Posted by TheMechanic

Is that a possibility, to lose power in turns? I know the slip additive allows more slip to eliminate chatter, but we're not talking about losing HP due to it ?

You're not losing horsepower, but think of it like you're not getting traction to utilize that power due to wheelspin.

[trebm3]

Originally Posted by Ximian

I do it about every year with Liqui Moly fluid. No noise or issues.

I put liqui moly in the diff and it made all sorts of noise in basic street driving. Went back to OEM and it's back to normal. Diff is very picky with fluids.

[TheMechanic]

Originally Posted by trebm3

I put liqui moly in the diff and it made all sorts of noise in basic street driving. Went back to OEM and it's back to normal. Diff is very picky with fluids.

I have the same experience... as I said. Not sure if ; at my driving level on track I will feel the difference between non limited slip fluids in the diff.. I do think I can get better lap times with driver training

[bigjae1976]

If you put in diff oil that's no slip or has no FM then you could have f'd your diff. The limited slip unit needs FM so the clutch plates will engage and disengage smoothly. Straight GL5 lube will cause abrupt engagement...hence the noise on tight turns...which will either burn up the clutches and steels or cause a lot of wear.

An E9X M3 differential, regardless of usage requires a GL5 lube with friction modifier.

For track use, the diff oil should be changed more frequently due to diff temps that likely get high, wear on the limited slip clutch pack and replenishment of the friction modifiers.

[kolosy]

so does the liqui moly stuff have an added friction modifier? don't need spend double on the bmw stuff if i don't have to, but that's the only one that explicitly calls out an FM / "friction booster"

Same q for the castrol OE FCP is selling -> https://www.fcpeuro.com/products/bmw...33117525064kt6

can't tell if i need separate friction modifier for that?

[spammysammich]

Originally Posted by kolosy

so does the liqui moly stuff have an added friction modifier? don't need spend double on the bmw stuff if i don't have to, but that's the only one that explicitly calls out an FM / "friction booster"

Same q for the castrol OE FCP is selling -> https://www.fcpeuro.com/products/bmw-differential-service-kit-e46-e90-e92-e93-genuine-bmw-33117525064kt6

can't tell if i need separate friction modifier for that?

I bought that kit. It has FM in it.

[amg6975]

My car sees almost no street time, but for years I drove it to and from the track and have probably done on the order of 200 track days with the non FM Redline oil. I sent two two-year samples to Blackstone and they said all was well within tolerance.

To each their own though, I do agree it probably increases clutch wear, and the possibility of issue. I would not run it on a street car. I'm willing to risk it on the chance it helps the OEM lock up a bit better until I move to an aftermarket solution.

[kolosy]

Originally Posted by amg6975

My car sees almost no street time, but for years I drove it to and from the track and have probably done on the order of 200 track days with the non FM Redline oil. I sent two two-year samples to Blackstone and they said all was well within tolerance.

To each their own though, I do agree it probably increases clutch wear, and the possibility of issue. I would not run it on a street car. I'm willing to risk it on the chance it helps the OEM lock up a bit better until I move to an aftermarket solution.

I was kind of wondering that also. So you run the straight 75-140?

[bigjae1976]

Originally Posted by amg6975

My car sees almost no street time, but for years I drove it to and from the track and have probably done on the order of 200 track days with the non FM Redline oil. I sent two two-year samples to Blackstone and they said all was well within tolerance.

To each their own though, I do agree it probably increases clutch wear, and the possibility of issue. I would not run it on a street car. I'm willing to risk it on the chance it helps the OEM lock up a bit better until I move to an aftermarket solution.

Are you using straight 75w-140 or 75w-140ns?

[TheMechanic]

Redline recommends the regular 75 140. I spoke to them once and they also mentioned that this is what we should use, track car or not. If I don't go oem next time, this is what I would use, with FM.

75W140 GL-5 Gear Oil - Quart
Popular for cars and light trucks like Ford Mustang and F-150, Toyota Tundra and Sequoia, Jeep Cherokee and Dodge Ram
Contains additional friction modifiers for suitability with clutch-type limited slip differentials - for most LSDs, no additional friction modifiers are required
This product is not designed for use in most manual transmissions or transaxles, since the extreme slipperiness may cause synchronizer mesh issues that lead to shifting problems
Recommended for API GL-5, GL-6, MT-1, MIL-L-2105E and SAE J2360

[amg6975]

Originally Posted by bigjae1976

Are you using straight 75w-140 or 75w-140ns?

Redline 75w-140NS

[bigjae1976]

Originally Posted by amg6975

Redline 75w-140NS

That’s surprising the limited slip unit would last with no friction modifier. I could see it helping with a badly worn LSD to help it lock up.

I can’t imagine how a diff oil analysis will give you feedback on the condition of the LSD unit except for if its damaged. Are they measuring clutch material levels? Clean diff fluid would indicate less clutch wear which would lead me to believe there is little engagement.

Have you checked the static preload?

[tsk94]

Originally Posted by amg6975

My car sees almost no street time, but for years I drove it to and from the track and have probably done on the order of 200 track days with the non FM Redline oil. I sent two two-year samples to Blackstone and they said all was well within tolerance.

To each their own though, I do agree it probably increases clutch wear, and the possibility of issue. I would not run it on a street car. I'm willing to risk it on the chance it helps the OEM lock up a bit better until I move to an aftermarket solution.

Have you noticed a difference in lock up with the NS? Assuming you've used both?

[amg6975]

Originally Posted by bigjae1976

That’s surprising the limited slip unit would last with no friction modifier. I could see it helping with a badly worn LSD to help it lock up.

I can’t imagine how a diff oil analysis will give you feedback on the condition of the LSD unit except for if its damaged. Are they measuring clutch material levels? Clean diff fluid would indicate less clutch wear which would lead me to believe there is little engagement.

Have you checked the static preload?

If you spin a wheel, the other spins the same direction. I haven't put much thought or effort into it. I assume if the clutches were shredding there would material in the oil but maybe not.

Been running it hard like that for like five years, no negatives to report.

Originally Posted by tsk94

Have you noticed a difference in lock up with the NS? Assuming you've used both?

I have not. When I did my swap I changed every fluid, and put in the NS fluid. It does make 11s, not 1s, when provoked.

[davieelikewat]

What's everyone using for 6mt transmission fluid for track cars? Redline MTL?