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PaulTWinterton

To Use Redline MTL or Not?

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I'm having a 4speed transmission rebuilt and want opinions on whether or not to use Redline MTL or a less viscous 75W-90 standard transmission fluid.

My rebuilder, who has 40 years of experience with BMW gearboxes says that the regular transmission fluid would be quieter and smoother shifting on a rebuilt box.

Yay or Nay?

Thanks,

Paul

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Never put straight redline MTL in a BMW gearbox. In fact you're supposed to use Redline ATF, never MTL in these. That said it eats reverse light switches and makes noise, I've heard of a 50/50 mix with normal-brand ATF works well though.

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Probably depends on the synchros being used, and what the builder says, if you want warranty coverage. GL-4 or not, that is the question...

I've used straight MTL in my 2002 and E30 M3 since 1997, and almost 200K combined miles, without issues. IME, it makes shifting easier in cold temps, and quiets down some noise. YMMV. According to Redline, it is safe for most cars with older-style brass synchros. Redline also recommends D4, so either way, you have a choice. I'd go with what your rebuilder says.

David

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Never put straight redline MTL in a BMW gearbox. In fact you're supposed to use Redline ATF, never MTL in these. That said it eats reverse light switches and makes noise, I've heard of a 50/50 mix with normal-brand ATF works well though.

Uh oh...been using MTL in my 02 gear box since my Rowe/Blanton Ultimate Transmission in 1983, at thier recommendation, actually came with the transmission. Never had any issues and as a GL4 gear oil, MTL does fine.

Earl

74 02Lux

02 M Roadster

72 Volvo 1800ES

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MTL is actually LIGHTER than 75- 90- it's darned thin.

I run it straight and uncut in everything I drive and race.

The one transmission it DIDN'T like was Jenn's Snoozookie Sidekick.

It got 'graunchy' and became notchy.

Changed it to MT-90 for somewhat improved performance-

she still didn't love it, but at 2.5 quarts, I was too cheap to

do it again to Snoozooki Flooid.

So it DOESN'T work in everything. But it works in 5 of our 6 BMW boxes

(the other one works great on D4)

t

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Andrey in Seattle freaked me out. Oh no! I've made my less than perfect gearbox even worse!

I have been told numerous times to use MTL in my well-used gearbox to ease the problem of shifting between 1st and 2nd. I've had it in there for a few weeks and all I notice is more noise as the gears are slapping around. No easy fix I guess.

Thanks for the replies. I will follow my transmission guy's advice and use a heavier fluid once the box is rebuilt. After all, this is ALL these guys do day after day, year after year. So they have probably learned a thing or two.

Cheers,

Paul

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Never put straight redline MTL in a BMW gearbox. In fact you're supposed to use Redline ATF, never MTL in these. That said it eats reverse light switches and makes noise, I've heard of a 50/50 mix with normal-brand ATF works well though.

Huh? if this is true then the vast majority of BMW transmissions at racetracks should have exploded a long time ago. MTL is probably the most prevelant fluid used in bmw gearboxes after the first drain of the the stock stuff.

i have run MTL in every manual tranny BMW i have owned, driven, tracked, raced, etc for decades. zero issues.

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MTL rocks, been using it for years... In BMW's

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MTL in all my BMW trannies, 2002s, E12s, E21s, E30, (M10, M20 and M42) E36 (M44, S52), track car, daily driver, fresh rebuilts, trannies with 300+K miles, no issues EVER.

CCA's Mike Miller highly recommends MTL in all manual BMW trannies. (At least through the E46s, IDK about SMGs.)

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On the later "ATF" tagged box in my E36, it got D4.

That worked.

I wouldn't be surprised if MTL did, too.

I'll try it when I get truly sick of getting slapped in the face by the headliner...

t

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Your owners manual tells you to run ATF, in fact any BMW with a Getrag box will have this recommendation. I've always used Redline ATF when I do use Redline but I try to water it down with plain ATF to keep the noise down and help my reverse light switches last longer. Redline is really good stuff, I know of a guy who lost a reverse light switch / plug on the track and emptied the gearbox, the residual Redline on the gears kept the the gearbox working and no visible damage was done, pretty amazing. I'm not sure that it's needed for "street" use unless you drive hard though.

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do you have some evidence/logic/explanation for why you think redline eats reverse light switches? i have never heard this conjecture before in any of my dealings with bmw's.

in my experience redline MTL and D4ATF decrease gearbox noises, not increase.

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