Type F or A fluid for Sachs Tranms?

Well, I've understood that Type F was the transmission fluid to use for Sachs. B.J. @ Handybikes just informed me that Type A (Dextron G.M.) is the fluid of choice that should be used in a Sachs engine. Anyone else uninformed and using Type F?

Re: Type F or A fluid for Sachs Tranms?

Danko Craig /

This doesn't answer your question. I have a tomos with a A35 and the booklet says to use type A, but I think type A fluid is from the 60's and not as easy to find. At least thats what I find. Tomos themself told me I can use type F where type A is specified.


Re: Type F or A fluid for Sachs Tranms?

Matt Wilson /

Type F.

Although after taking the transmission apart, I really think that you could put just about any oil in, and it would work fine.


Re: Type F or A fluid for Sachs Tranms?

Type F for sachs

Not dextron III


Anyone think there would be a problem using 90wieght gear oil in the sachs tranny? Thats what i did seems to work fine.

I personally don't belive in ATF in gear boxes, manual Trannys for a Chevy (p.o.)s. 10 are $1800.

Re: 90W???

do NOT put 90w (or 80w) in the gear box.

use type f for: sachs, puch

use 20w for: minarelli

use 30w for: morini, garelli

Re: 90W???

Yeah, 90 weight might not be the best thing to put on the CLUTCH and gears in a sachs.

Re: 90W???whynot?

why? any reasoning

Re: 90W???whynot?

90w oil is far too thick. i'm not sure what technically it would do to the engine ... but i can't imagine it being good.

ATF is fine

Chuck wrote:


> I personally don't belive in ATF in gear boxes,

Thats funny .. what do you think is in the automatic trannies of 90% of the vehicles on the highway ?

(with multiple gear sets .. and friction clutches .. transmitting 100 or 200 times the power of a wimpy little moped with ITS automatic tranny)

> manual trannys for a Chevy (p.o.)s. 10 are $1800.

So?.. these aren't manual trannies are they ?

ATF is PERFECT for 2 stroke moped trannies.

and the debate over Dexron or type F ATF's is like the difference between a 100 million dollar lottery prize and a 100.01 million dollar prize .. anybody who thinks theres some big difference for a moped is clueless.

(including some moped shop)

And even 90 weight gear oil is OK.. as long as it your clutch doesn't slip... you're fine.

The endless arguing of the trivialities in a 2 stroke gearboxes oil is freakin ridiculous.

Remember though .. ATF is the ONLY oil that is designed with friction clutches transmitting power in an oil bath .. in mind.

Now I understand.

Fred thank you for the explanation. Not only did you inform me not to put 90w in my case... you told me why. I like that. I personally would not have made the connection between Automatic trannys, their fluids and the wet clutches in the moped.

tell you what I'll drain the 90w and try some ATF.

Re: Type F or A fluid for Sachs Tranms?

The floowing tranny fluids are listed in the Sachs Prima G3 manual as acceptable in the Sachs engines:



Shell Donax T6

Castrol TQ

Mobil Fluid 200Y

DEA Fluid 684 (ATF)

Sunoco Transmatic-Fluid AQ-ATF 7373A

These are numbers from the 1970s and may have been replaced by newer formulations.

ATF type F should be ok.


Re: Type F or A fluid for Sachs Tranms?

A side note:

Puch specified ATF type F for their moped clutches in the 70s. They advised against using other types of lubricants, because they may result in slipping or dissolving of the liners. The clutching linings are often particles of cork or other material pressed and held together by a binder. Using the wrong type of tranny fluid or unusual types of fluid (power steering fluid, brake fluid, etc) could dissolve the binder and cause the lining to crumble apart.


Well hold on now ..

Well dude .. actually I said 90w gear oil is OK as long as your clutches don't slip.

I heard of motorcycle racers using 90w gear oil in the gearbox on their 2 stroke race bikes about 5 years ago ... I was very surprised .. and asked them several questions about how it worked and if the clutch ever slipped while the motor was hot.. or cold... Nope.. worked great.

(and I KNOW the 90w will lube the gears as well as can be)

That is just about the day I bnecame firmly convinced that virtually any oil in a 2 stroke gearbox... manual or automatic... works fine.

.. and if your clutches slip... go to a lighter weight oil .. or ATF.

Drained my F and put in A...

As an experiment, I swaped my F for A and I have to say that my Sachs runs smoother and nicer. The F only had about 100 miles on it, so I know it wasn't old and dirty.

Looks like Bob Jones at Handybikes might be up to something with his A type recommendation. It may have something to do with the way that type A actually flows compared to type F.

Anyway, I've changed and I'm glad I'm glad that I did.

Re: Drained my F and put in A...

Type A has a slightly lower friction coefficient that F, so it would make sense that it seems smoother. Type F was made by Ford for minimal clutch slip. I believe type A was orignally used by GM.


Re: Drained my F and put in A...

Hi Dennis.

Thanks for letting us know how it worked for you.


gear vs. motor oil viscosity

Gear oil viscosity is measured at 150 F whereas motor oil is measured at 210 F. 95 W gear oil is comparable to 40W motor oil.


Drained my F and put in A...

Well, I guess if it works, it works.

The reason I use type F is because I've always heard and read that Dextron/mercron was abrasive. I figured the type F would make things last longer. That may not be the best theory with a clutch, tho, Right?

Thinking about it, How abrasive could tranny fluid be?

I'll try it- Hell, if it messes up, I have enough spare parts to re-do my clutch anyway.

Re: Drained my F and put in A...


Interested to hear what you think about the F to A switch once you've had a chance to put on a few miles. Hope to hear from you.

Re: gear vs. motor oil viscosity

Paul I would really liek to know your source for that. Do you have the ASTM standards book. That statement seems pretty fishy.

Buy the way I swapped out the 90W for ATF and I really had to crank down the preload on my sachs clutches to get that "snappy" engagement. The preload that I had on the clutches w/ 90w just dragged and dragged to engagement on the ATF.

Re: gear vs. motor oil viscosity

ASTM Method D445 defines kinematic viscosity.

SAE defined at what temperature the viscosity is measured for a particular class of oil. SAE assigned grade numbers (such as 40W) to particular ranges of viscosity.

SAE defined a lower test temperature for gear oil compared with motor oil, since gear oil generally operates at a lower temperature. Lower temperature means higher viscosity and a higher grade number. It is the difference in test temperatures that causes gear and motor oil of the same viscosity to have different grade numbers.

The webpage below shows a table of SAE grades assigned to viscosity ranges for gear oil (it's called axle lubricant in the table). The graph at the very bottom of the page shows which grades of motor oil (graph calls it crankcase oil) and gear oil have the same viscosity.



Re: Drained my F and put in A...

hmm, so what does this mean for my puch?

Re: Drained my F and put in A...

dexron III replaced Type F AND Type A(also used by Mopar) eventually. Not for 'friction' reasons, but because The automotive companies required somthing more durable than either. Ford and GM both superceded those with Dexron/Mercon V in 1997, even more durable stuff, designed for 5 and 6 speed automatics (more clutches, planetary gearsets and hydrualic controls than most of you could comprehend). that' what I'm running in my Cosmo. Smoth shifting, and I KNOW it won't deteriorate the rubber parts inside

as for gear oil, GM 'posi-traction" units have clutch plates inside of them designed specifically for use in hypoid gear lubricant (the proper name for 'gear oil') motorcyles have been useing oil bath clutch plates since the first time they made the gear box and the crankcase together in one piece...

If what you're using in your gear box doesn't mess it up, then go for it.

oh and BTW, BOTH ford and GM Used Borg-Warner 5 speed MANUALS in the Camaro Z-28 and Mustang GT and LX V-8 back in the late 80's/early 90's that used Dexron III and didn't have Any problems unless went all out and doubled the horsepower of the engine and Dogged the car Power shifting at every light....

Re: Drained my F and put in A...

Well, I went and tried it.. Not much of a change. I think the clutch slips a little less.

Re: Drained my F and put in A...

I use 95-120 w oil in mine. but .. my trans is a 2 speed manual shift ...

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