Manual tranny oil + diff oil - Redline FTW

[dzenno@PTF]

Decided to check on the rest of the fluids yesterday and change out the tranny and diff fluids.

Firstly the tranny oil...When my stock clutch went I had a ClutchMasters FX400 with their 16lb aluminum lightweight flywheel put in. That lasted about 4,000km on the car and died prematurely (was warrantied later, alas)...due to some chatter from the flywheel I went the UUC cocktail way for the tranny oil (1 bottle Redline 75W140NS and 1 bottle Redline D4ATF). As far as I can recall the cocktail didn't help chatter much if at all but I left the oil in there for about 50,000km now. Didn't have much issues except recently I noticed that in colder weather a REALLY fast WOT 1-2 shift was next to impossible to nail right. The shifter would almost go into gear but not quite. No grinding while doing that, it just wouldn't engage 2nd gear fully. This wasn't the case just regular/spirited driving on the street, however, it would happen 4 out of 5 times at the drag strip and I was losing it especially when at the end you realize you missed that shift on a 1.70 60' According to advice of many, I changed this oil yesterday for just pure 2 quarts of Redline D4ATF. It is a bit thicker than the OEM 6MT BMW tranny oil, thinner than the UUC cocktail, and I have to say its doing wonders now and I should've done this a long time ago. I guess the UUC cocktail was just a bit too thick for those hard 1-2 shifts. Even city driving shifting feel has noticeably improved. As for the previous cocktail mix, the fluid itself was amazingly clean when it came out. I expected it to be dirty or somewhat dirty, thing came out almost as clean as when it was put in so I won't complain much in that respect...

One other thing, I also got the basic black rubber tranny mounts from UUC Motorwerks and will be changing out the stock hourglass type really soft tranny mounts...a tiny bit of extra vibration is expected and as this is my daily driver I didn't want solid/poly mounts there as it'd vibrate too much for my taste...the idea behind tranny mounts is the following..once you've missed quite a few 1-2 shifts you start looking at the shifter and look at what's happening with the tranny as the motor unloads from 1st to go into 2nd...torque in the 1st gear twists the tranny quite a lot and you can actually see the shifter move to the side under heavy load of that 1st gear...now couple that with trying to move the shifter down into 2nd FAST you're more likely than not to miss that 2nd gear and $#@! it up...tranny mounts should keep the tranny more firmly in place and prevent this from happening, well hopefully and without much additional vibration over stock...we'll see how that goes once I get them installed, no rush at this point...

As for the diff oil, a bit of a shocker after seeing how clean the tranny oil came out...original diff oil filled was OEM and it came out BLACK and disgusting...the Wavetrac diff that I have, once really hot, would be a tiny bit noisy which you could hear only in complete silence in the car and only on decel, just a tiny bit of gear whine but I got used to it...well, yesterday after replacing the OEM diff oil with Redline 75w-90NS (also recommended by Wavetrac along side the OEM fill) that decel whine is also a lot better to a point where its not noticeable...I have no idea why/how BMW can claim that their diff oil is lifetime. I can see how it could be for the tranny, maybe, but the diff, no $#@!ing way...i'm planning on changing that oil every 30-40,000km going forward, no lifetime BS there...

Change your diff oil people

[bulldog x6]

did the same this summer - good preventative maintenance I guess. Ill be changing trans fluid every summer now to keep things smooth....

[Yukohama]

good to know for the future! Thanks!

[Tzu]

My tranny oil @55k was surprisingly clean, minus metal fragments which were worrying. Agree with the diff oil. It was black, worn, and smelled uniquely horrible.

[uniter]

How'd you drain the diff?

[dzenno@PTF]

Take the plug off and use a hand pump to pump the fluid out

[Bash]

What diff oil do you recommend on stock car? no LSD here.

[dzenno@PTF]

Either OEM or Redline 75w-90NS as indicated above...if you want to do regular maintenance and save a few bucks I'd do Redline

[uniter]

I was hoping you were going to tell me to flip the car over X) Thx.

[dzenno@PTF]

I was hoping you were going to tell me to flip the car over X) Thx.

or that lol