[Tambohamilton]

What are our options for OE LT3 transmission oil nowadays? BMW want £46.46 for 2L of the stuff, which isn't the end of the world, but it's a lot more than the ~£10-15/L for most other oils.

If I could find out what the genuine stuff is nowadays I'd probably settle for that, but Castrol BOT 207 (ref. ZF TE-ML 11) doesn't seem to exist any more...anyone know what the current equivalent is?

Castrol Syntrans B states ZF TE-ML 11 compliance...but TE-ML 11 covers a lot of specs!
Syntrans FE also looks like it'd fit the bill, but says nothing about any BMW/ZF specs.

Just to add some confusion, Fuchs Titan Sintofluid 75w - 80 specifies itself as a replacement for MTF-LT3...and it's 75-80 wt. So does Millers TRX Synth 75w....?!?

I guess any of the above will do nicely and I won't be able to feel the difference (other than in my wallet), and the tranny won't eat itself...but I just want to know!

Thanks for any help!

P.S. No, I'm not interested in any Redline etc ATF, even if it's largely the same thing as I need.

[robnitro]

Te ml 11 sounds like they spec a synthetic atf.
If you can get GM syncromesh, that is much better. They used that to fix syncro issues on the corvette tremec transmissions and it's worked well on my friend's m5 e60 smg box. He was using the bmw stuff and later redline mtl which gave him issues with shift quality.
Syncromesh was much better than the expensive vw fluid in my mk4 TDI.

[Tambohamilton]

Interesting... I'll look it up. Thanks.

My box is just starting to crunch a little on shifts into 2nd/3rd, so I guess any help on the syncro will be beneficial.

[Tambohamilton]

Hmm, it doesn't look like GM synchromesh is readily available to me (in the UK), or really the stuff for the job...though it may well work properly etc.

Happened upon some very interesting information from MolaKule on Bob Is The Oil Guy...

Most differential and Manual Transmission oils contain sulfur-phosphorous EP packages. GL4-rated oils contain about 40% to 60% of that amount; the other difference is the Friction Modifier.

Both differential and manual transmission fluids use chemical compounds that subdue or inhibit the corrosive effects of sulfur such as calcium, magnesium, boron, potassium or other basic compounds. Emulsifiers, corrosion and rust inhibitors also are included to do their respective jobs.

Differential lubes use friction modifiers to reduce mechanical and fluid friction and add some anti-shudder friction modifier for limited slip, both very different chemical compounds.

Manual Transmission fluids use a different friction modifier for synchro engagement, a modifier that does NOT contain the same chemicals as differential lubes.

Differential lubes use friction modifiers to reduce mechanical and fluid friction and add some anti-shudder friction modifier for limited slip, both very different chemical compounds.

Manual Transmission fluids use a different friction modifier specifically designed for synchro engagement, a modifier that does NOT contain the same chemical compounds as do differential lubes.

Both lubes generally contain the same TYPE EP additives, just in different strengths or additive ratios.

Most manual transmission "specific" fluids (GL4) contain about 40% to 60% of the EP additive of differential lubes (GL5) with inactive or buffered sulphurs. GL4 has come to infer a gear lube with the above percentages of EP additive. The exception of course is ATF fluid used in some of the newer transmissions.

You also have to consider the viscosity of the fluid that the transmission was designed for. The spectrum now ranges from ATF to 75W90 viscosities.

Ever since the synchromesh-type fluids appeared on the scene (such as the GM Synchromesh fluid), drivers have had better shifting due to better synchro engagement, attributed to the specialized friction modifier used in these lubes. This specialized friction modifier is better for metallic and composite synchros in terms of shifting and life.

A diffy 75W90 (GL5) usually has a higher viscosity than does an mtl in the same advertized weight.

So a differential lube may not kill your tranny, but it is not the optimum lube.

GL4 does NOT refer to any specific viscosity, but it refers to a level of AW/EP protection for the gearing and bearings in a transmission.

A synchromesh GL4 Manual Transmission Lubricant (MTL) can be any viscosity from 7.0 cSt (ATF equivalent viscosity) to a 75W90 type viscosity of approx. 14.5 cSt, and contains special friction modification additives for synchronizer assembly engagement.

A synchromesh fluid usually refers to a specialized fluid that contains special friction modification additives for transmissions that use mechanical synchronizer assemblies; those synchronizer assemblies may be made of carbon fiber composites, sintered metal, brass/bronze, or steel-steel materials.

Current MTL GL4 viscosites are:

1. ATF Series - Type; 6.5 to 8.5 cSt (Equivalent ATF viscosity; Note: ATF additive package is weak compared to most GL 4's)
2. Synchromesh Series -Type; 9.3 - 9.5 cSt (such as Amsoils MTF, Texaco's MTL, Pennzoil's Synchromesh, GM and Chrysler's Synchromesh)
3. 75W85 Series-Type; 9.8 to 11.5 cSt ( Redline's MTL, RP's Synchromax LT, Nissan's MTL, Honda MTL, Castrol Syntorq LT)
4. 75W90 Series-Type; 12.8 to 14.5 cSt (Amsoil's MTG, Redline's MT-90).

MTL specific lubes we're developed for manual tranny's and transaxles, and not for differentials or industrial gear boxes.

Doesn't really get me any further forward, but highlights why oils intended as ATF probably aren't a great replacement for MT oils which are a similar viscosity....as well as a bunch of other interesting bits.

[robnitro]

Good stuff from bitog!

Way back when I had a Honda the Honda guys swore by the honda MT fluid.
Redline MTL was ok but not as good as synchromesh. Pennzoil also makes a syncromesh but not sure if it exists in the uk.

[Tambohamilton]

Looks like the Pennzoil stuff is VERY similar to the GM stuff... potentially Pennzoil made both. Again, it's a bit rare in the UK, so more expensive than the Fuchs and Millers oils which are a decent match for LT3.

From the bitog info above, I think Honda MTF is a fair bit thicker than the LT3. Thanks for the input, robnitro.

Surely somebody knows what happened to Castrol BOT 207??