Yep......and start with checking the o ring seals around the drain plugs and primary chain case.

 

Surf city made th best post. They are different and the tranny fluid is more in line with a gear oil. Even though AMSOIL says 20/50 in all three, they are still aware that folks want to do their own thing and not operate that way. Call it a marketing scam if you like, but I call,it smart business and appealing to their customers desires by offering a different, specific product for each hole. I made my choice before I got smart on the new products by picking one of their severe gear oils for the tranny and an auto trains fluid for the primary or else I would have gone with these bottles as well. No regrets though. Can't go wrong either way. I'd be curious to see how close the primary fluid is to a tranny fluid or if it's more similar to an oil.

 

Super heavy gear lube, GL4, GL5, Hypoid Gear oil on and on... None are needed to protect the lightly loaded gears in a Harley transmission.

Somebody please show me a pic of a gear worn prematurely due to using engine oil in the transmission, on anything...

You will sometimes read about and/or see failures in HD transmissions, and almost always it is a bearing failure.

From the sound of this question, it appears that you have little experience repairing the drivetrains on these machines, so how does the color of the lube on the floor help you?

A good Harley Davidson mechanic will know how to find where the leak is coming from, without any color coding...

 

Why it is so difficult to accept that they come new with three different oils?! Perhaps I'm getting too old, but in fifty years of riding bikes I have never had any difficulty with following the bike manufacturers recommendations, even if I don't always use the recommended brands. Why reinvent the wheel - er oil....... Jus' sayin'.

 

What oil specification does the MoCo call out for use in Engines, Transmissions, Primary (not the viscosity grade, but the actual oil spec)?

An actual Spec, API, SAE, ILLSAC, JASO?

Or do they simply say they recommend genuine Harley etc?

 

Dan, you probably know the answer to that! We are advised to use H-D branded stuff, but many well-known brands offer products directed at us Harley owners, so it is dead easy to select suitable products, rather than go down blind alleys chasing obscure choices. I've only owned Harleys for 42 years, it ain't difficult.....

 

They come new with 3 different oils ?

They really DO come new with 3 different oils ??

Call me pedantic, but this could possibly mean something.

 

Well, now you are going to have to find 3 holes to put them in.

 

I used to use Syn in the primary but started thinking why would I put an oil that's made to slip in a primary with a clutch that's made to grab? It may seem to work, but I think you will encounter slippage.
I use Lucas Dino primary oil and Amsoil VTwin Syn Tranny. Amsoil or Mobil1 or Royal Purple Syn in the motor.
Whatever is on sale and saves me a few bucks for bling!

 

From Amsoil tech dept...

The three Harley fluids are not "all the same 20W50 oil" As you can see the primary and transmission fluids are of different speciations and viscosities than is the 20W50 V-Twin oil;

Viscosity of motorcycle lubes.

What is the viscosity of AMSOIL V-twin Primary Fluid (MVP):

MVP has the physical characteristics of an SAE 50 weight motor oil. This does not mean it can be used in engines. This is merely a reference to its viscosity that is universally understood. Refer to the data sheet for further product features.


What is the viscosity of AMSOIL V-Twin Transmission Fluid (MVT):

MVT has the physical characteristics of a 110wt gear lube. It has gear lube properties but it is NOT a spec rated gear lube. It has been designed to perform in the transmissions used in today's separate sump v-twins.

You ca also look at the Data sheets for the three products and see other comparisons between them.