Originally Posted by OneM
After my run-in period, I changed the transmission fluid to the recommended BMW MTF LT-5. Didn't make much of a difference as the gearbox was still notchy, especially going into 2nd gear.
As the BMW LT-5 isn't a synthetic oil I researched other BMW forums that recommended the use of Redline's synthetic transmission oil. On Redline's website itself, their application guide for our 1M's recommends the use of their 'D6 ATF'. And I know ATF stands for 'automatic transmission fluid' but on the rear of the bottle it does say for manual transmissions too.
So I gave it a shot. My my.. and I ain't exaggerating when I say this, its pretty much night and day difference. Mostly after after a couple of days usage. Not only is it smooth going into gears the vehicle's performance and mileage improves due to its lower resistance. And that's something you can feel.. the lower resistance and smoother acceleration.
Now I know there'll be skeptics out there which is fine. I'm here just sharing my personal experience and I believe that's what forums were created for. So for those who only stick to OEM fluids that's perfectly fine too. For others willing to give it a try, I'm sure you'll be pleasantly surprise by this synthetic oil.
I tried Redline in place of LT-2 in my E46 and it made a great difference in late August. Once October and November rolled around, I did not like it's cold properties. The shifter felt gummy until the car warmed up which was usually when i was pulling into my parking space at work. Too little, too late. I think the bigger concern is that LT-5 was especially formulated for the 1M and they were very specific about it. I believe there was some new coating in the gears that they were concerned about and the previous MT fluid was not compatible with it....You just put some of the older stuff in your gearbox. Yes it's synthetic but not sure how wise it is especially under warranty. Also, Redline has a red color which is a tell-tale sign if you experience transmission problems and they see the stuff. I hope it works out.
I recently replaced my fluid with LT-5 and while picking it up, the parts guy told me there was an LT-6 that supersceded LT-5. I didn't confirm, just asked him for the LT-5 but it might be worth looking at that instead of potentially ruining your gearbox and getting caught in a warranty debacle. At this point it will take more than one gear oil change for the fluid not to have a red tinge to it. Cars that were accidentally filled with LT-3 by the dealer, I believe were offered extended warranty on gearbox.
Good luck, truly hope I'm wrong on this one.