ATF in MT ?
- Thread starter Ndx
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BMWs have been using ATF in their manual transmissions for a long time.
As I understand it: ATF's main weaknesses are that it's thin and usually doesn't provide as much protection against shock loading as a typical gear oil. However, some manual transmissions are designed to spread the loading out across a lot more gears than normal. That reduces the load on each individual gear tooth, which lets you use a thinner fluid with less shock loading protection like ATF.
There are also the typical benefits of thin oils in general: they cool better, flow better in tight bearings, and produce less drag on rotating parts.
As I understand it: ATF's main weaknesses are that it's thin and usually doesn't provide as much protection against shock loading as a typical gear oil. However, some manual transmissions are designed to spread the loading out across a lot more gears than normal. That reduces the load on each individual gear tooth, which lets you use a thinner fluid with less shock loading protection like ATF.
There are also the typical benefits of thin oils in general: they cool better, flow better in tight bearings, and produce less drag on rotating parts.
That's right.
It's what's specified for BMW manual gearboxes.
I'm using RP Syncromax in my 328i which still performs well in the cold.
It's what's specified for BMW manual gearboxes.
I'm using RP Syncromax in my 328i which still performs well in the cold.
JHZR2
Staff member
Some do, some dont. Not all BMWs take ATF either... There are alternatives to ATF that have a similar viscosity profile, but are more heavily additized.
Originally Posted By: Ndx
I heard recently ... That some of the Car Manufactures are recommending ATF in Manual Transmission ..
Sounds like [censored] ?
Gee, that's ancient and very common practice, not [censored]. Mopar recommended ATF in the A-833 (muscle-car era) 4-speed and its overdrive version way back in the early 70s. ATF is also recommended for many of the New Venture Gear manual transmissions used in GM and Dodge pickups today.
High-sulfur gear lubes are incompatible with the synchronizers in many manual transmissions.
I heard recently ... That some of the Car Manufactures are recommending ATF in Manual Transmission ..
Sounds like [censored] ?
Gee, that's ancient and very common practice, not [censored]. Mopar recommended ATF in the A-833 (muscle-car era) 4-speed and its overdrive version way back in the early 70s. ATF is also recommended for many of the New Venture Gear manual transmissions used in GM and Dodge pickups today.
High-sulfur gear lubes are incompatible with the synchronizers in many manual transmissions.
Yep. My 1988 manual trans full size Chevy pickup with a getrag trans used ATF.
An auto trans has gears no matter what that sounds like.
Redline and Amsoil recognize ATF is used in MTs and have formulated their products accordingly.
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D4 ATF also provides a GL-4 level of gear protection, making it a superior product for transmissions and transaxles
Quote:
D4 ATF also provides a GL-4 level of gear protection, making it a superior product for transmissions and transaxles
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Nothing new at all. GM vehicles running the T56 are the ones I deal with most often.
Using ATFs in MTs is nothing new but the synchronizer materials have to be taken into account. ATF is a compromise because it gives good low temperature shiftability but it may not provide the ideal friction characteristic for some synchro materials.
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Still wondering why manufacturers dont have a thin gear oil but with strong additive packages for EP and AW qualities. Take a look at VOA's and I believe even some of the better ATFs dont have NEAR the additives the gear oil SPEC'D for many transmissions. Half way through 2005 dodge changed transmissions fron the NV 5600 to the MB G56, even though they both deal with 610lb-ft of torque,one specs basically a gear oil and the other atf? Now I know Im no engineer and I wish I knew more about the design parameters of BOTH transmissions but this I DO believe: Maybe Mercedes designed their transmission from the ground up for atf and maybe NV didn't BUT if the one needs a robust additive package for long service life (as any fluid recommended for the NV5600) then SO DOES the OTHER! I dont believe that given the same application one can be engineered in such a way as to not require additives for protection and longevity. There should be a light weight gear oil with a additive pack suitable for transmissions.
"Still wondering why manufacturers don't have a thin gear oil but with strong additive packages for EP and AW qualities ... There should be a light weight gear oil with a additive pack suitable for transmissions."
They do. Royal Purple Syncromax. And Molakule also produced an ATF-thin synchromesh fluid when Specialty Formulations was in business.
They do. Royal Purple Syncromax. And Molakule also produced an ATF-thin synchromesh fluid when Specialty Formulations was in business.
Yes it seems RP Synchromax is a good alternative, I thought when I filled my Corolla that it was GL-4 and GL-5? I cant remember. If so then there should be a good amount of both EP and AW. My point was more along the lines of the fact that the most of the ATF transmissions run fairly regular ATF fills like say Mopar ATF 4+, these fluids I believe has very low levels of EP and AW, so most vehicles are running weak fluids.
My 88 E-150 5 speed uses ATF.
Originally Posted By: Whitewolf
ATF is a compromise .....
Wow! There's something I thought I would never read. Whitewolf saying a factory spec'ed ATF is a compromise.
I've been using the RP Synchromax in my SRT-4 for the past few months and have been quite pleased with it. Admittedly, I have no way of knowing how that will work out long term but a light synchromesh fluid is designed specifically for a manual trans. and ATF simply isn't. The factory spec's ATF+4 plus 4 oz. of LS friction modifier for proper synchro operation (the limited slip is a Quaife torque biasing unit that doesn't use clutches so doesn't require the FM) and they call for a change interval of only 18k miles. This definitely sounds like a compromise to me.
ATF is a compromise .....
Wow! There's something I thought I would never read. Whitewolf saying a factory spec'ed ATF is a compromise.
I've been using the RP Synchromax in my SRT-4 for the past few months and have been quite pleased with it. Admittedly, I have no way of knowing how that will work out long term but a light synchromesh fluid is designed specifically for a manual trans. and ATF simply isn't. The factory spec's ATF+4 plus 4 oz. of LS friction modifier for proper synchro operation (the limited slip is a Quaife torque biasing unit that doesn't use clutches so doesn't require the FM) and they call for a change interval of only 18k miles. This definitely sounds like a compromise to me.
Originally Posted By: TheForeman
Still wondering why manufacturers dont have a thin gear oil but with strong additive packages for EP and AW qualities.
Well, there's Redline MTL and Royal Purple Synchromax for light-oil manual transmissions, and Redline MT-90 for heavy-oil manual transmissions without the sulfur additives of GL-4 and higher gear oils.
But I don't see why you seem to think that gear oils HAVE to be heavy for HD applications. Viscosity means little, film strength means everything, and the actual requirements depend on subtleties of the transmission design (syncrho materials, gear tooth profile, contact area, bearings/bushings, etc. etc.). Typically, manual transmissions don't have ANY hypoid gears at all, so there's absolutely no need for a GL-5-like fluid which is specifically tailored for the extreme pressure SLIDING contact that exists only in hypoid gears, not spur or helical gears. The very additives that are essential for hypoids are destructive to many synchro materials.
Still wondering why manufacturers dont have a thin gear oil but with strong additive packages for EP and AW qualities.
Well, there's Redline MTL and Royal Purple Synchromax for light-oil manual transmissions, and Redline MT-90 for heavy-oil manual transmissions without the sulfur additives of GL-4 and higher gear oils.
But I don't see why you seem to think that gear oils HAVE to be heavy for HD applications. Viscosity means little, film strength means everything, and the actual requirements depend on subtleties of the transmission design (syncrho materials, gear tooth profile, contact area, bearings/bushings, etc. etc.). Typically, manual transmissions don't have ANY hypoid gears at all, so there's absolutely no need for a GL-5-like fluid which is specifically tailored for the extreme pressure SLIDING contact that exists only in hypoid gears, not spur or helical gears. The very additives that are essential for hypoids are destructive to many synchro materials.
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MolaKule
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I had one of the first S-10 pickups produced in 1982 (Engine and transmission was an Isuzu) and the transmission used ATF.
Since GM or Pennzoil Synchromesh (9.3 cSt) fluids are only about 2 cSt higher than ATF (7.5 cSt), I recommend trying it in transmissions that spec ATF, since the GM or Pennzoil Synchromesh fluids have about three times the AW and EP additives, and are synthetic blends.
Since GM or Pennzoil Synchromesh (9.3 cSt) fluids are only about 2 cSt higher than ATF (7.5 cSt), I recommend trying it in transmissions that spec ATF, since the GM or Pennzoil Synchromesh fluids have about three times the AW and EP additives, and are synthetic blends.
I had a 89 ford ranger 4x4 2.3 liter 4 banger that had ATF in the transmission, also a 94 4x4 with a 4.0 that also had atf in the transmission, never had any problems out of them other than the built in weakness of rubber grommets at the top, replaced them with freeze plugs at slave cylinder/clutch change around 140,000 on both.
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