Transmission Fluid vs. Gear Oil?

Jamez · 05-08-2015, 04:26 PM

I've searched around on the forums here and have yet to find a thread that covers this. If I missed it, I apologize. It's time for me to replace my trans fluid / gear oil and I'm a little confused. Gear Oil is much thicker and Trans Fluid is much lighter. But which one do I use? It sounds like for Scooters, located towards the back that you insert Gear Oil and NOT Transmission Fluid. My owner's manual says otherwise? :o

Can someone explain this to me?

bull · 05-08-2015, 05:40 PM

In your manual just below #5 it says "Transmission 90". The 90 is a viscosity index and it is what is generally called 'Gear Oil'. You could use 75w90 and be fine. I use synthetic in all I service.

Transmission fluid as generally accepted term for autos is about 5 viscosity on older fluid types and less than that on new synthetics like +4 and such.

Jamez · 05-09-2015, 08:17 AM

So Gear Oil and Not Transmission fluid?

Shadowfire · 05-10-2015, 02:54 AM

The manual is quite specific. You want to use SAE 90 weight oil, which will almost certainly be sold as "gearbox oil" or "transmission oil".

Jamez · 05-10-2015, 10:18 AM

Quote:

Originally Posted by Shadowfire

The manual is quite specific. You want to use SAE 90 weight oil, which will almost certainly be sold as "gearbox oil" or "transmission oil".

Okay so I'll just search for SAE 90 and hopefully that solves my problem.

wheelbender6 · 05-10-2015, 11:54 AM

Automatic Transmission fluid is basically hydraulic fluid. An auto transmission contains a hydraulic pump, so that the fluid can actuate different parts of the transmission. Auto transmission fluid is only able to adequately lubricate drive gears when placed under pressure by the hydraulic pump. That is why an auto transmission will very quickly wear out if the hydraulic pump goes bad or the seals wear out.

rks · 05-10-2015, 01:22 PM

Quote:

Originally Posted by Jamez

Okay so I'll just search for SAE 90 and hopefully that solves my problem.

You won't have to search far.....any big box store, or your favorite auto parts place will have it....even comes in a one quart bottle with a little squirt top. That size bottle will be enough for about 5 changes.

05-10-2015, 11:54 AM	#6
wheelbender6 Join Date: Mar 2010 Location: Houston area Posts: 945	Automatic Transmission fluid is basically hydraulic fluid. An auto transmission contains a hydraulic pump, so that the fluid can actuate different parts of the transmission. Auto transmission fluid is only able to adequately lubricate drive gears when placed under pressure by the hydraulic pump. That is why an auto transmission will very quickly wear out if the hydraulic pump goes bad or the seals wear out. __________________ "Beer never broke my heart" - Luke Combs
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05-08-2015, 05:40 PM	#2
bull Join Date: Feb 2015 Posts: 257	In your manual just below #5 it says "Transmission 90". The 90 is a viscosity index and it is what is generally called 'Gear Oil'. You could use 75w90 and be fine. I use synthetic in all I service. Transmission fluid as generally accepted term for autos is about 5 viscosity on older fluid types and less than that on new synthetics like +4 and such.
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05-10-2015, 02:54 AM	#4
Shadowfire Join Date: Feb 2015 Posts: 121	The manual is quite specific. You want to use SAE 90 weight oil, which will almost certainly be sold as "gearbox oil" or "transmission oil".
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