ATF for tranny fluid

[Mick Milakovic]

My shop manual says to use ATF in the tranny  of my 250cc MC5.  I don't doubt this, but was wondering, does ATF work well in all bikes?  My 390 Huskys say to use straight weight 20w, and I don't know about my kids' late model stuff.  I hate to use the fluid that shops call "clutch saver" because of expense.  I've been running ATF in the trans of my daughters' KX-80 and KX-60 because they are just not hard on their bikes.  What about other bigger and newer bikes?

Mick Milakovic
Delphi, IN
765-268-2570
[email protected]

[Doug Wilford]

Pay now or pay later  It would be much safer to use the Golden Spectro 80W Gear lube.  It is actually a 10W 30W, we used it in all of the Penton race team bikes for years.

 

[dirtbike]

This thing has been discussed in recent MX and dirtbike magazines a whole lot. I have personally never damaged an engine from using ATF fluid but I do have an interest in properties, tests and reports and the chemical properties for different oils. The ATF oil is better for the clutch but doesn't have the lubricating properties that a gerbox really requires. I believe that your KTM has sintered plates. In that case you need to change the oil almost every time you ride. I change the oil every time on my KTM 500MX using cheap automotive motor oil. My engines looks brand new when opened. There are better oils out there but plain engine oil is anyway far far better then ATF from this perspective. The thing is, sintered plates and used oil is a bad thing regardless of what you payed for the oil. You just end up with a more expensive grinding paste. Most japanese bikes or read (fiber clutch plates) can be ridden several times on the same oil. The contamination doesn't damage the engine in the same way but the oil looses it's lubricating properties. It will almost always be better than ATF anyway. If your clucth doesn't slip with normal engine oil, use it. From what I have read you can mix in ATF at 15%, 25%, 50% and so on to correct a slipping clutch.
Keep it at a minimum if you have to use it at all.

 

[Dwight Rudder]

UNDER NO CIRCUMSTANCES USE A MODERN AUTOMOTIVE OIL IN YOUR MOTORCYCLE. THIS IS HIGHLY NOT RECOMMENDED! Modern ( since 1975 ) have contained increasing amounts of what they call friction modifiers. This is like STP oil treatment. These modifiers are fine for gears but HELL on a wet clutch. Automotive oils are not designed for the same oil to lube gearbox , wet clutch and sometimes the engine also. Use motorcycle specific oil in your gearbox. ATF is ok in some circumstances but isn't the greatest stuff for the gearbox. Barely enough for the gears. Some gearboxes require ATF or they don't function properly. Ball Shifters like a Zündapp will not function with oil. The balls don't drop into place fast enough. If in a bind you can use a Diesel oil like DELO 400 or SHELL Rotella, in as light a oil as they have.  These do not have Friction Modifiers as automotive oils do.  Best thing is to use a Motorcycle Gear oil as Doug recommended. In a 80wt or 75wt gear oil. These are similar in consistancy to 10w30 engine oil.
Cher'o

Dwight Rudder
7 time ISDT / E medalist
7 time National Enduro Class Champion.

[Dwight Rudder]

quote:
UNDER NO CIRCUMSTANCES USE A MODERN AUTOMOTIVE OIL IN YOUR MOTORCYCLE. THIS IS HIGHLY NOT RECOMMENDED! Modern automotive oils ( since 1975 ) have contained increasing amounts of what they call friction modifiers. This is like STP oil treatment. These modifiers are fine for gears but HELL on a wet clutch. Automotive oils are not designed for the same oil to lube gearbox , wet clutch and sometimes the engine also. Use motorcycle specific oil in your gearbox. ATF is ok in some circumstances but isn't the greatest stuff for the gearbox. Barely enough for the gears. Some gearboxes require ATF or they don't function properly. Ball Shifters like a Zündapp will not function with oil. The balls don't drop into place fast enough. If in a bind you can use a Diesel oil like DELO 400 or SHELL Rotella, in as light a oil as they have.  These do not have Friction Modifiers as automotive oils do.  Best thing is to use a Motorcycle Gear oil as Doug recommended. In a 80wt or 75wt gear oil. These are similar in consistancy to 10w30 engine oil.
Cher'o

Dwight Rudder
7 time ISDT / E medalist
7 time National Enduro Class Champion.

Dwight Rudder
7 time ISDT / E medalist
7 time National Enduro Class Champion.

[dirtbike]

Oops, I wouldn't want to argue with Dwight Rudder or Dough Wilford about this. Let's just say that these two opinions here pretty much reflects the answers you will get asking around. A good motorcycle oil is, of course, a safe route to stay away from trouble. Me for myself use automotive oil that meets the SL specs and with a low Zink percentage content. Two articles about this is here: http://www.yft.org/tex_vfr/tech/oil.htm
and
http://www.ducatimeccanica.com/oil-James.html

Anyway, if you are about to race or ride hard go for the more expensive motorcycle oil. Dwight Rudder knows something about the Zundapp gearbox that makes ATF an option there, but in your KTM?? I need to hear a good explanation if so.