Offers and thoughts on Gearbox and Diff Oils?

[Fishy Dave]

Hi,

I'm likely to carry out an Inspection 2 service on my M over the Christmas break and wondered what the current thinking is on recommended diff and gearbox oils? It's only been 11 months since I carried out the Inspection 1, but the transmission fluids haven't been changed for a few years now. Any links to offers or specific products?

Thanks, Dave

[bradz]

Millers.

http://www.millersoils.co.uk/which-oil

Changed mine and it made a big difference. I just used the recommended ones by millers.

I was considering Redline/Royal Purple but after speaking with a gearbox builder who said the boxes that come back with redline/RP have more wear on the ones run with millers oils. Make of it what you will!

Adam

[Mangozac]

I went for the BMW MTF-LT3 gearbox oil. My research and discussions with BMW techs indicated that it's 100% compatible. I have a post somewhere on here about it. The Z4M box is the same used in the Z4 3.0si and a bunch of other cars, all of which have LT3 oil specced. People generally expect the Z4M to have the same box as the E46 M3 because they both have the same engine, and the M3 box is definitely not approved for LT3.

For the diff I used Castrol SAF-XJ. No friction modifier additive and it's still behaving itself (no noises when turning). Only 1.5L is needed so a friend and I bought 3x 1L bottles and split it

[Mangozac]

I was considering Redline/Royal Purple but after speaking with a gearbox builder who said the boxes that come back with redline/RP have more wear on the ones run with millers oils. Make of it what you will!

I too have heard that Redline and Royal Purple are not ideal for longevity. Good for racing if you're going to change it frequently.

[Scooba_Steve]

I put some Castrol in the box at about 70k, original fluid was nasty. Just put red line in and may have some analysis done in 15/20k.

[Mangozac]

I put some Castrol in the box at about 70k, original fluid was nasty. Just put red line in and may have some analysis done in 15/20k.

70k (miles I presume) is very late to be changing out the original fluid. It's supposed to be done as part of inspection 2.

[Spock]

I used these last year:

Castrol Syntrax Longlife 75W-90 Fully Synthetic Car Gearbox Oil
Motul Motyl Gear SAE 75w-80 Fully Synthetic Car Gearbox Oil

Delivered from Opieoils, price seemed good at the time. I think the Castrol went in the diff.

[srhutch]

I put some Castrol in the box at about 70k, original fluid was nasty. Just put red line in and may have some analysis done in 15/20k.

70k (miles I presume) is very late to be changing out the original fluid. It's supposed to be done as part of inspection 2.

Going by the sig that’s on a non ///M

[Mangozac]

Going by the sig that’s on a non ///M

Bloody non-M drivers posting in the M specific section!

Still, I have heard of confusion from M owners of whether their gear fluids require changing.

[srhutch]

Going by the sig that’s on a non ///M

Bloody non-M drivers posting in the M specific section!

Still, I have heard of confusion from M owners of whether their gear fluids require changing.

...and shims aren’t changed during an inspection 1.

It’s all smoke and mirrors

[Fishy Dave]

Thanks guys For the benefit of others searching this thread, the M takes 75w-140 oil suitable for LSD in the diff and 75w in the gearbox. Fully synth in both. I'm probably going to opt for Millers Nano, but will compare to costs from the dealership when it re-opens on Wednesday.

[Beedub]

im going to switch engine oil now, i see no benefit anymore for the BMW spec stuff....

Gearbox and Diff i stuck with stock as i had some spare left over, the difference to the change was insane, did not expect such a noticeable change to shift quality.

Have just done engine, and gearbox fluid change for my ST and the difference is again huge.

[Argenta]

Super happy with:

Engine: Castrol TWS 10w-60
Box: RedLine MTL 70w-80
Diff: Motul Gear Competition 75w-140