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Discussion Starter · #1 · (Edited)
So having just changed all the plugs and filters I wanted to give the gearbox fluid a change too as it's probably never been done before. Having had good experiences with redline MTL in my previous m3's I decided to try it in the m5.

Initial thoughts after the change were that it felt ok, about the same as before I had changed the fluid. However after a few cold mornings it became apparent that my gearbox felt considerably more notchy especially going to 2nd gear when cold. It was a bit notchy when cold before but not this bad. So I decided to try some Motul 300, an oil i have heard good things about.

After the change and after trying it cold for a few days I can say that it was better but still not as smooth as when the original fluid was in there - or had I forgotten how good/bad it was? I now was beginning to doubt myself too.

Anyway there was only one thing left to do. Buy some LT2 from BMW (all 5 litres, ouch!).

So after changing the fluid for the third time and having driven the car for a few days now I can conclude by saying that the BMW LT2 fluid has made my gearchanges feel significantly better than the previous 2 attempts. It's even good when cold and my 2nd gear is also sweet.

I know other members will have different experiences with the fluids I've tried but this is just my 2 pence worth!
 

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Interesting insight. I just change my fluid with Royal Purple SyncroMax and it was a small improvement, however, I am going to experiment with a 50/50 mix of Royal Purple SyncroMax and Royal Purple 70W90 and see how things play out.
 

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Isnt that improvement with the RP synchromax because the oil is thinner and not doing as good a job at protecting the moving parts, thicker oils feel more notchy when cold?
 

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So having just changed all the plugs and filters I wanted to give the gearbox fluid a change too as it's probably never been done before. Having had good experiences with redline MTL in my previous m3's I decided to try it in the m5.

Initial thoughts after the change were that it felt ok, about the same as before I had changed the fluid. However after a few cold mornings it became apparent that my gearbox felt considerably more notchy especially going to 2nd gear when cold. It was a bit notchy when cold before but not this bad. So I decided to try some Motul 300, an oil i have heard good things about.

After the change and after trying it cold for a few days I can say that it was better but still not as smooth as when the original fluid was in there - or had I forgotten how good/bad it was? I now was beginning to doubt myself too.

Anyway there was only one thing left to do. Buy some LT2 from BMW (all 5 litres, ouch!).

So after changing the fluid for the third time and having driven the car for a few days now I can conclude by saying that the BMW LT2 fluid has made my gearchanges feel significantly better than the previous 2 attempts. It's even good when cold and my 2nd gear is also sweet.

I know other members will have different experiences with the fluids I've tried but this is just my 2 pence worth!

IIRC LT2 is very thin compared to MTL, I don't know anything about the Motul though. Thicker gear oil would make it shift stiffly when cold.
 

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I thought the sticker on the side of the transmission said LT1. I also think I read somewhere that BMW hasn't officially recommended LT2 as a replacement for LT1. This last bit is more fuzzy in my mind though.
 
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I used Silkolene Silktrans in my Coop as it was a forum favourite, cold shifting was stiff (a weaker person might have struggled to find 1st, or 2nd from 1st) but once warmed up it was great, smooth shifting and quiet. That box had 130k on it too, and never had an issue while I had the car.

I'm still planning to use RP as it just seems to get good reviews on here, and I'm not going to argue with other peoples experience.
 

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I thought the sticker on the side of the transmission said LT1. I also think I read somewhere that BMW hasn't officially recommended LT2 as a replacement for LT1. This last bit is more fuzzy in my mind though.
LT2 replaced LT1 it's LTF2 isn't it?
 

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I have Redline in the MX5 (Miata) and the gearchange is incredibly notchy when cold - a significant amount of strength is needed to even engage reverse gear.

On the M5 I did a change to RP last weekend. I can confirm the experiences of others that it indeed makes the shift smoother and lighter. Almost too light, in fact - I actually prefer a meaty, weighty action, not a car that I can shift gears with just the tips of my fingers.

The Redline is definitely much thicker than something like RP - you can feel the difference pouring the fluid from the bottle and pushing it through the pump.
 

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Interesting thread. I have had my 2001 with 100k miles for 3 Canadian winter months now and I am not enjoying the notchy 1-2, 2-3, 3-2 shifts when cold. Tomorrow morning will be -10 deg C so I know the 3-2 shift will be damn near impossible for a mile or two. Don't know what oil is in the tranny now, but I have the RP Synchromax ready to go in - fingers crossed.
Anyway, my question is to those who have had new/low mileage M5's: was the shift buttery smooth when new? Is the notchiness just the effect of 100k on the synchro rings? Or was it always notchy 'cos its a heavy duty tranny?
 

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Hi,

I got fed up of a notchy g/box when cold. Tried various.........nothing really helped.

The best I found was RP Synchromax with an apropriate dose of Activ8 in there.

Even in very cold weather , 1st to 2nd changes work much much better.

linky to Activ8 and no i have no vested interest at all in any way.

Activ8 Friction Reducer - Engine and Gearbox Oil Additive - Increase Engine Performance Power and Economy - Reduce Wear in Engines and Gearboxes - Suitable for Cars - Motobikes - Lorry Engines and Gearboxes has many Mechanical Uses

Regards

Nat.
 

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Interesting thread. I have had my 2001 with 100k miles for 3 Canadian winter months now and I am not enjoying the notchy 1-2, 2-3, 3-2 shifts when cold. Tomorrow morning will be -10 deg C so I know the 3-2 shift will be damn near impossible for a mile or two. Don't know what oil is in the tranny now, but I have the RP Synchromax ready to go in - fingers crossed.
Anyway, my question is to those who have had new/low mileage M5's: was the shift buttery smooth when new? Is the notchiness just the effect of 100k on the synchro rings? Or was it always notchy 'cos its a heavy duty tranny?
You likely have the original fluid. I changed mine for the BMW fluid and shifting was much, much better everywhere. This will happen with nearly any fluid though.
 

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On the M5 I did a change to RP last weekend. I can confirm the experiences of others that it indeed makes the shift smoother and lighter. Almost too light, in fact - I actually prefer a meaty, weighty action, not a car that I can shift gears with just the tips of my fingers.
Lol, some folks are never happy ;)
 
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