Thread revival time!
Stay with me... this is kind of epic.
I've been researching this manual transmission and differential lubricants thing ad nauseum.
I have a '09 335i 6MT. My tranny is labeled for MTF-LT-3 (Castrol BOT 207) and the OEM diff oil is widely known to be Castrol SAF-XO.
Searching for info or specifications on MTF-LT-3 or Castrol BOT 207 yielded nearly nothing. I did find one guy on BITOG who did a VOA on LT-3. The viscosity tested at 6.1 cSt @ 100ºC.
I did find some interesting things though in the one Castrol PDF that mentioned BOT 207:
Quote:
The team settled on a fluid known as BOT 207.
Tests on a rolling road showed lower fuel consumption when BOT 207 was used. There was a 1.4 per cent improvement in fuel efficiency over the fluid normally used in the BMW Mini...
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Then the go on to talk blah blah about saving 3 grams of CO2 per kilometer. That'll really save the world. Obviously the change to LT-3 is motivated by efficiency.
Quote:
Fill-for-life already exists for passenger cars, which typically have a life expectancy of 200,000-250,000km.
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LOL! Caught 'em red-handed! Fill-for-life my arse! Who's life are we talking about here? If you want to keep your car longer than 124k ~ 155k miles, you'd better change that transmission oil.
Also, for the 1 Series M Coupe, the official BMW maintenance schedule is to change the transmission oil every 30k (50k km). The 1M uses a ZF GS6 transmission similar to the one in my 335i (but not the same box).
So, I'm really frustrated that the only way to get MTF-LT-3 is to buy 5 liters. My car is still under factory warranty (49k) and will be CPO thereafter. So I've wanted to use the factory fill lubricant. No OEM alternatives available.
As for the Diff, SAF-XO seems to be discontinued. The new Syntrax Longlife 75W-90 is unobtanium in the U.S. The BMW branded fluid is available if you want to buy a 55 gallon drum for about $2k.
The only alternative is to buy Land Rover LRN 7591 which is Castrol SAF-XO for about $20 a quart. I think I'm just going to do Red Line for the diff. Their 75W-90 NS has almost exactly the same viscosity as the SAF-XO
SAF-XO
KV @ 40ºC: 100
KV @ 100ºC: 15.2
Red Line 75W-90NS
KV @ 40ºC: 95
KV @ 100ºC: 15.6
Red Line 75W-90
KV @ 40ºC: 112
KV @ 100ºC: 16.1
Any reason to go for the more common 75W-90 that's intended for limited slip diffs (which I don't have, obviously) instead of the 75W-90 NS "No Slip"?