This stuff: Results first: holy cow, this stuff really cuts down the gearbox rattle that comes with installing a one-piece lightweight flywheel. Now, first off, I know that this oil may not match MINI's recommended oil specs for the gearbox. I know in fact that it is not a one-to-one replacement for the OEM oil. Also, I am hoping not to start a "my favorite brand is better than your favorite brand" oil-powered flame war here. On to the story. I've tried out several types and viscosities of gearbox oil in my 2003 S over the years. At first the goal was to quicken the shift, and I had settled on Redline MT90 for several years. The shifts were lightening quick, I have to say. I have had a lightweight, one-piece flywheel on the car for years now, and of course I have also had the gearbox rattle that comes with that. Over the last two years, I have become less tolerant of the noise. It was really starting to irritate me. The gearbox shifts fantastically and does not overheat or make steel shavings (the oil comes out seemingly as new when drained) , but oh, that noise! It's annoying, especially when the AC is on during a hot day. One solution I tried was a mix of Redline MT90 and 75-140NS, as suggested over on NAM (and I think, originally suggested by a prominent MINI parts vendor). Shifting was still excellent, but the effect on noise was very small. Last week, I decided to "go for the throat" and try Heavy Shockproof. This is an oil with a heavy suspension of anti-friction particles in it. I swear, it looks like slightly dark Pepto Bismol. The base oil is roughly a 75W90 weight, but the particle suspension (according to Redline, read more in the white paper at Redline ) acts like a 75W250 oil in the way it provides high film strength. This oil (along with the lighter variants) is very popular in some circles, particularly off-road applications and in Harley Davidson gearboxes. To be sure, I was worried about shifting speed after reading all of Redline's promises about lower friction. I want an oil to cushion the gears (to lower the noise), but I don't want the oil to screw up the action of the syncros. So, I made sure to have the usual oils on hand for a quick change back to normal if the Shockproof oil was a disaster. Well, the Heavy Shockproof is still in the gearbox. I'd say it cut the noise down by more than 3dB, or more than 50%. I found myself at times paying very close attention to the car, trying to hear the noise at all. To be sure, the noise is still there under heavy deceleration (as with one's foot off of the throttle, engine at 5000 RPM, down a steep hill) and also I can hear a bit of noise when at a stop light, AC on, car all warmed up. Still, it's a massive improvement. I'm still trying to decide if the switch to the new oil affected the shifting at all, so therefore the effect is very small. I'm inclined to say that shifting is very, very slightly slower, as one would expect, but perhaps I'm just biased towards that conclusion. Now, it may be that my gearbox is on the outs, and sooner or later it will make so much noise that I'll have to rob the college fund to pay for a new one. However, since the noise itself has hardly changed in the last couple of years, I suspect that in a few years that gearbox will still be in the car, and my ears will be grateful for the oil change.