Manual transmission oil change

[tomjonesBT33]

Picked up a Z4 M roadster at the beginning of Dec. Prior owner had done a good bit of work to get it running and driving like new. I’ve been working through some gremlins (that don’t affect drivability) to get the car in near perfect working condition. One example is that the reverse lights weren’t working - I was able to track the issue to the switch located on the transmission. Fixed that a couple of weeks ago. While doing this, I noticed the transmission oil was VERY dirty. Though the PO said that he changed all the fluids, I have a hard time believing the trans fluid was changed. See pic of the oil I removed today. Replaced the oil with Red Line MTL. Haven’t been able to drive it yet, but just rowing the gears while in the garage, I can tell it’s shifting much smoother.





Replaced old oil with this. It’s 75W80 and has a slight red tint. Kinda looks and flows like ATF fluid, which BMW also says is compatible with this gearbox. Will see how it holds up. I’d actually like a bit thicker oil, so may try MOTUL 75W90 next time.

 

[RedUn]

It probably hadn't been changed for ages before the last change...if you dropped it again in 100 miles it might be the same but after that it would probably stay clean for a decent amount of time...

Or they just didn't change it :roll:

 

[Mr Tidy]

That looks pretty dirty - as RedUn said I'd be surprised if it had been changed.

My transmission oil looked like this after 29,000 miles!



Given how yours looked I'd have a look at the differential oil as well.

 

[tomjonesBT33]

Thanks fellas. I’ll be changing the rear diff this weekend. Fluid arrives tomorrow. Castrol Syntrax. I’ve ordered 4L of the Red Line too. I plan to drive it maybe 500 miles and change it again. Hopefully then it’ll be good for 30K. I plan to make it a 30K regular maintenance item.

 

[Wassup]

I went down the route of using a mixture of redline MTF and redline ATF D4 having previously used this in my E46 M3 manual gearbox. Shifts are much smoother than before.

You can get a bottle of both for approx £40 which is pretty reasonable.

 

[Adam D]

I went down the route of using a mixture of redline MTF and redline ATF D4 having previously used this in my E46 M3 manual gearbox. Shifts are much smoother than before.

You can get a bottle of both for approx £40 which is pretty reasonable.

M3 has a different getrag gearbox, vs ZF in the 3.0si/z4m