final say on fluids used in ATF-specced MTs

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JHZR2

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Hello,

Ive been trying to decode the truth of using fluids other than ATF in MTs specced for ATF.

The unit in question is the 5-speed MT in my BMW, specced for ATF. IIRC it is a getrag 240.

The question is really, what are the compatabilities between ATF and synchromesh fluids, and what issues might arise from using a synchromesh fluid in place of ATF?

My understanding from reading back in the archives to 2003 (essentially all of Molakule's posts) is that ATF is mainly specced for cold weather feel properties, not for AW protection. OK, fine, got that...

But that said, are there any potential issues from using synchromesh fluid in place of ATF? Lots of folks run redline MTL, so I know the higher viscosity of such a fluid (say 10 vs. 7.5 for an ATF) is OK in terms of shift feel and performance.

Im concerned about long-term reliability using say, Amsoil MTF vs. ATF.

Thanks for your input!
 
I've been using Royal Purple Synchromax in my transfercase which is spec'd for ATF+4 for the past 100k.

RP is the thinnest of the synchromesh fluids I found...MTL is the thickest.
 
I would say there are no issues with using MTF because in all but the coldest temperatures, the Δ vis vs. Δ T is not that huge, sure at 100°C MTF is 9.6 cSt, and ATF is around 7.5 cSt and at 40°C it's 47 and 32 respectively.....I just think in a manual tranny you get way better gear protection with an MTF.
 
In almost all cases, a synchromesh fluid [or similar] is better than ATF in a manual tranny.
I can't see it being otherwise.
Better protection and shifting.
Remember, you are not stocking a dealership with a single simplistic ATF for auto trannys, power steering systems, transfer cases, and manual trannys.
 
Been running Amsoil MTF in my ATF spec. trans for the last year. Love it.

Most of the OEM spec. ATF's have a cold tolerance out to ~20000 cSt so the slightly thicker sychromesh fluids will be no problem unless you get into the very low -F's. Plus, they carry EP packages that ATF's do not have.
 
If you are going with Redline, I'd use MTL over their ATF fluid in any manual tranny. I've had good results with the MTL. Yeah, I'm sure it requires a bit more effort in shifting for really cold temperatures, but every BMW guru I've ever read says it offers better protection. Mike Miller says go with MTL in a manual tranny BMW, if that means anything.

Amsoil's manual tranny fluid is probably just as good. I just haven't used it, so can't comment on it.
 
Isn't BMW MTF on the thicker side also? ~10cst @ 100C? There was a VOA in the gear oil forum but I can't find it.
 
my BMW MT specs ATF explicitly. Coding AF3 - this correlated to a dexron III type fluid, as well as others.
 
I agree with mechtech, mtl specific fluids always offer better AW protection than ATF.

I would try a low viscosity MTL in the 9.3 to 10.5 cSt range.

If cold weather shifting is a problem, one alternative is to mix a synthetic ATF (7.5 cSt) with a synthetic MTL (around 10 cSt) about 50/50. At least the AW levels would be greater than ATF alone.

They may be bulding the ATF app. manual trannies better now, but I had three rebuilds on an S-10 tranny while I had it, and the S-10 had a weak 4 banger in it.
 
OK, to add to this, here are two others...

A saab which uses MTF 0063, which Mola characterized in my VOA/UOA as a very light 75w-90, and a VW, which uses a fluid which it looks like is characterized simply as a "75W" lube, vice other VW-spec oils which are explicitly 75w-90. It is unclear if the "75W" oil is 75w-75, 75w-80, etc. Any thoughts?

For the Saab, for example, the amsoil 75w-90 MTL looks too thick, the 5w-30 synchromesh looks too thin. Redline MTL looks a bit thin too.

For the VW, Redline MTL might be the stuff, but is there a real issue with using a slightly lighter fluid if full torque is not regularly obtained?

Also, specific to the Amsoil fluids, their 5w-30 is explicitly a synchromesh fluid, whereas the 75w-90 doesnt say it. Is it nieve to say that most any MT made for PC use in the last 10+ years is "synchromesh"? Perhaps the design requires slightly less or more viscosity, but how big of a deal is it?
 
During my quest for an oil to use in the Astra, which takes the GM Transaxle stuff here and Castrol 75w-90 overseas, I went with Silkolene Pro SRG 75 Ester Race oil. A thin MTF that still has GL-4.

It seems the "specs" differ widely across the ocean, from thick there to thin here, so I took the middle road. In hindsight, Syncromesh is ideal to bridge the ATF/MTF gap, but usually Redline MTL is what I think of first.

Here is what I trolled up for the Saturn forum...

M1 ATF = 36.3cSt at +40c, 7.4cSt at +100c, super-thin.

PZ Syncromesh = 41.6cSt at +40c, 9.8cSt at +100c, mid-thin range.

Read the first paragraph from Pennzoil:"Suitable for all GM"
http://www.pennzoil.com/documents/Sy...ns Fluid.pds

Redline MTL = 56.2cSt at +40c, 10.2cSt at +100c, Thicker than Syncromesh

http://www.redlineoil.com/Products.aspx?pcid=7

SRG 75 = 68.7cSt at +40c, 10.65cSt at +100c, Thicker than Redline.

http://www.opieoils.co.uk/pdfs/PRO SRG 75.pdf

Plug them into widman's visc calc and reduce the temps to below zero.

http://www.widman.biz/Seleccion/Visc...aph/graph.html


I copped this of another forum, just the hot viscs...

http://forums.tdiclub.com/showthread.php?t=132884


10.6 = Redline MTL 70-80
13.8 = Amsoil MTG 75-90
15.2 = Motul Gear 300 75-90
15.6 = Redline MT-90 75-90
15.0 = Elf Tranself Synthese FE 75-90
16.7 = Motul MOTYLGEAR 75-90


You can see how 75w-90 is not even in the ballpark as ATF substitute.


Thinner to thicker is:

M1 ATF (unless AMSoil is thinner, but I dunno)
PZ Syncromesh
Redline MTL
Silkolene SRG 75

Syncromesh is likely the best choice for ATF trans service and is cheap compared to Redline, but I don't think anyone would regret buying the Redline.
 
Originally Posted By: JHZR2

Also, specific to the Amsoil fluids, their 5w-30 is explicitly a synchromesh fluid, whereas the 75w-90 doesnt say it. Is it nieve to say that most any MT made for PC use in the last 10+ years is "synchromesh"? Perhaps the design requires slightly less or more viscosity, but how big of a deal is it?


MTF is a GL4 MT fluid ~9cSt - similar to MTL.

MTG is a full 75W90 GL4 MT fluid ~15cSt - similar to MT-90.

Both have the synchro-optimizing FM pack, as far as I can tell. This FM pack is all manufacturers are referring to for "synchromesh" fluids - not a viscosity characteristic.

I don't believe Amsoil has an ATF visc ~7cSt synchro FM fluid. But then, are there any cars which actually need it that thin? Some MTs have stickers for Dexron/ATF on them but I believe this may be simply for convenience, not that 7cSt is actually required.

Redline specs D4ATF for my BMW, but all of the BMW MTFs are 9-10cSt, not 7. Dave@Redline indicates they spec ATF for easy shifting in all temperatures. He explains that less technical customers may not understand that MTL or MT-90 may not shift as well in very cold conditions and they don't want to generate customer complaints. Dave says in terms of compatibility and FM pack function, MTL and MT-90 would be great in Getrag and ZF manuals and encouraged me to try them as a "more technical" customer. MTL has been fine in my BMW down to -25C. Honestly it was better than D4ATF. Lots of BMW owners in more temperate climates run MT-90 and love it.

Royal Purple Synchromax didn't impress me at all, despite its iconic fanboy following in BMW forums. Most of these folks would see the improvements they see changing to fresh ANYTHING, not just Synchromax, but I digress. After only about 25,000km (not mi) the stuff came out noticeably thinner than it went in, and it already starts thinner than the MTFs BMW recommends.
 
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I would say that a mild visc upgrade in almost ANY gearbox will add to long term reliability. The only cons is the 1st couple of cold morning shifts.

For those of you that insist on using ATF, stick with a full synthetic.

Some 7cst substitutes are Torco MTF & MTF-L, and Royalpurple Synchromax.

And, there are ATF's that are ~10+cst. Try Amsoil CTJ, Redline High-Temp or Racing ATFs.... so you can feel good about using ATF but know that its synchromesh thick!
 
For my BMW, I've found that amsoil mtf is optimal, seemingly retaining shift characteristics for longer than redline mtl, and more importantly, no first gear whirring sound.

I'll need to verify the viscosity of the vw fluid, the Saab is a light 75w-90, but given the excellent mileage characteristics, I don't want to take a big hit.

The Saab/gm mtf required for my 9-3 is mtf0063. My voa and uoa Is here:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1347471
 
Originally Posted By: Audi Junkie
During my quest for an oil to use in the Astra, which takes the GM Transaxle stuff here and Castrol 75w-90 overseas, I went with Silkolene Pro SRG 75 Ester Race oil. A thin MTF that still has GL-4.


Silkolene SRG 75


for my Saab, nothing really matches to the mtf 0063, which is a differentfluid than gm synchromesh.

That SRG fluid seems like it may be a good option for the Saab and vw.

I won't change from the amsoil in my BMW, as the mtf truly is excellent for that. My fear is that it is a bit light for the saab and vw. Meanwhile the amsoil 75w-90 seems a bit heavy, and while I care about protection, coldweather shifting is important.
 
JHZR2 - Some very odd manual trannys use an oil pump. More than a few use carbon fiber or paper synchros.
They need the thinner ATF, even though ATF is not the best manual trans sauce.

For most of us, upgrading is smart. A synchromesh type is not real thick. Better wear and shifting are ours to be obtained.
 
For my applications (other than the BMW), ATF is not specified, so I guess Im safe there.

Are you saying that a 75w-90 MTF, if shiftable, is really the best for all applications?
 
Too bad there is no PDS for that motorcraft oil. In reality, Saab/GM MTF0063 is fine for me. My only fear being with saab going to new owners, what happens to the fluid spec and how do I get the right fluid. Draining the fluid out on a 9-3SS isnt as easy as in most other cars due to the location of the drain plug...
 
Has anyone tried the new Ford dry clutch fluid for DCT's?

It has an ATF range viscosity but its additive package is definately that of a synchromesh fluid.
 
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