Z4M transmission fluids

[pal]

I've used factory fluids for the transmission and differential and it's worked out fine. Car used to see a lot of track time for about 6 years and sits at 90K miles on the odo. now.

diffsonline.com sells the OE diff fluid in single use quantities.

[bosstones]

I swapped out the OE fluid for Syncromesh a little while back. It came at the recommendation of my SA who was also a track rat. I didn't find a lot on it wrt Bimmer forums but what little I found was not bad. I didn't notice much of an improvement and will be open to swapping it out for something of a more known quantity in the future.

[XMetal]

Originally Posted by bosstones

I swapped out the OE fluid for Syncromesh a little while back. It came at the recommendation of my SA who was also a track rat. I didn't find a lot on it wrt Bimmer forums but what little I found was not bad. I didn't notice much of an improvement and will be open to swapping it out for something of a more known quantity in the future.

I guessed some have this issue and others don't. You might be one of those lucky one who's fine with the OE fluid

RP Synchromax made a world of difference on mine. I have hated 2nd gear from day 1. It had a grinding feeling from the shift lever about 50% of the time if I shift below 4K with the OE fluid. It felt the same after swapping out the OE fluid at around 23K with Pentosin MTF2. The Synchromax, on the other hand, felt awesome after replacing the Pentosin at ~44K. I don't have to role the dice or cringe on every 2nd gear shift anymore and it's so much more enjoyable to drive it now

[bosstones]

Originally Posted by XMetal

I guessed some have this issue and others don't. You might be one of those lucky one who's fine with the OE fluid

RP Synchromax made a world of difference on mine. I have hated 2nd gear from day 1. It had a grinding feeling from the shift lever about 50% of the time if I shift below 4K with the OE fluid. It felt the same after swapping out the OE fluid at around 23K with Pentosin MTF2. The Synchromax, on the other hand, felt awesome after replacing the Pentosin at ~44K. I don't have to role the dice or cringe on every 2nd gear shift anymore and it's so much more enjoyable to drive it now

I wouldn't complain if I was. Still, though, Synchromesh hasn't allotted me any noticeable benefit. Synchromax is what I thought of trying next. I don't get what I would call a grinding feeling, just that the is "notchy". The car in general shifts better around 4k+, though...and not a slow acceleration where one simply waits until to 4k+ to shift (if that makes sense). I always figured it was just the engine/trans pairing or the car was just happier being driven a little more spirited.

I swapped the trans fluid out about 4k miles ago. The car is waiting for the threats of snow to stop so it can hit the streets again. I'll re-eval once that happens. Morning commute temps are good enough these days (low 40's) where I'd be comfortable driving on summer tires. Need to get this layer of sawdust off first, though......my fault for not covering the car while using the garage to cut all the baseboard/quarter round when I replaced it all on the 1st floor... Oh....looks like I finally need a new battery, too......not bad for 9.5 years.

[Manxman1950]

I just replaced the gearbox and diff fluids with Redline (MTL/MT90 mix and 75W140). I now detect a soft "chunking" noise from the rear when negotiating highway on and off ramps, which wasn't there before the change. My understanding is the the Redline fluid includes friction modifiers, so my question is - is this likely to go away with further use, or should I change back to OEM?

[XMetal]

Our diff is so finicky with fluids - that's why I don't like to veer away from it unless there's a major reason to do so.

I think only you can decides if it bugs you enough to have the fluid changed. My understanding is that the slight groaning during sharp turns is "OK"

[kaybat]

used Pentosin mtf 2 sae 75w-80 for tranny, works fine

[David70]

Enthusiast Auto replaced my transmission fluid with Redline MTL and my diff is listed as 75W90 (I believe from BMW) with 505-7478 Diff Fluid Additive - added for limited slip

[Westersund]

Originally Posted by David70

Enthusiast Auto replaced my transmission fluid with Redline MTL and my diff is listed as 75W90 (I believe from BMW) with 505-7478 Diff Fluid Additive - added for limited slip

M Coupe should have 75W-150 fluid in the diff with LSD additive. It's the regular BMW's that use 75W-90.

[StickMon]

[Manxman1950]

Originally Posted by Manxman1950

I just replaced the gearbox and diff fluids with Redline (MTL/MT90 mix and 75W140). I now detect a soft "chunking" noise from the rear when negotiating highway on and off ramps, which wasn't there before the change. My understanding is the the Redline fluid includes friction modifiers, so my question is - is this likely to go away with further use, or should I change back to OEM?

Update - I decided to allow some time for the diff to bed in with the new fluid, given the good experience reported by other users of Redline products. I am pleased to report that this has worked out well and the previously mentioned noise has now gone.

[Caddyshk]

Originally Posted by StickMon

Attachment 1496619

SAF-XJ with FM Booster should only be added if you have a noisy diff. My experience is it caused undue slip and engaged DSC in corner exits at that track. I purged it all out with Motul over 2 changes and a couple of hundred miles 2 years ago and have been pleased.

[Caddyshk]

I've had RP in the transmission for about 7 years now. IIRC I've swapped it out twice.

[XMetal]

Originally Posted by Caddyshk

I've had RP in the transmission for about 7 years now. IIRC I've swapped it out twice.

Glad to hear that it held up well