Oil Grade

baldric · #1 09-17-2009, 08:23 PM

My brother has a 2009 Fat Bob. He had the oil changed on the first service and was wondering if the 20W50 in the motor is the same oil used in the tranny? The reason he asks is the dealer insists it's the same in both holes and he has his doubts. Don't reply with the " get a service manual" It's on order as we post.

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Heath · #2 09-17-2009, 09:18 PM

Must have done the Syn3 20/50? That one they can in all THREE holes. As long is it is wet clutch compatible as most motorcycle oils are, it can be used in the primary. It can be used in tranny as well but many use gear lube. He's good.

baldric · #3 09-17-2009, 10:04 PM

Thats good to hear. Damn I forgot about the primary. When he asked me he was more concerned about the trans so I never even thought of the primary. Thanks.

1550vt · #4 09-18-2009, 04:34 PM

If they put the syn 3 in all three holes, they need to go back to Harley School. I believe the MOCO no longer recommends that. They had some transmission issues running the 20w50 in the transmission. They did it despite of the warnings from the motorcycle world-at-large that it was too thin. Personally, I tried it and got to the end of my driveway, came back and changed it to gear oil. Sorry to say it was Amsoil, but I am not trying to start an oil argument as I think syn 3 would have netted the same results. I don't think anything but a good grade of gear oil should be in the transmission and some guys run 85 and others run a multi-viscosity like a 75w-140. It's fine for the primary, but HD is using a product called Pro Gold now and may even be putting the same in the transmission. I would ask myself, if I had a car with a manual 5-speed transmission, would I put motor oil in there.

Having said this, I am sure there are lots of folks out there running the 20w50 in all three holes with no issues. I just could not do it and make mine shift and I know of many others that would not do it either. Transmissions will perform differently using various types/grades of lubricants and your brother will find out what works best for him as time goes by.

1550vt · #5 09-19-2009, 08:46 PM

I realized that I misspoke in the above post. HD is using Formula Plus in both the primary and the transmission and not Pro Gold. My local dealer no longer puts the syn 3 in the transmission and since Harley has discontinued the primary fluid, the replacement product is the Formula Plus.

pococj · #6 09-19-2009, 11:42 PM

Quote:

Originally Posted by 1550vt

(Snip some) They did it despite of the warnings from the motorcycle world-at-large that it was too thin. (Snip some) ...and some guys run 85 and others run a multi-viscosity like a 75w-140. (Snip some)

Are you aware that engine oil and gear oil viscosity scales are not the same? The viscosities can not be directly compared. 20w-50 engine oil is about the same actual viscosity as 75 - 90 gear oil. And 140 gear oil is generally equivalent to 60 motor oil.

SAE Engine Oil vs. SAE Gear Oil

10w thru mid range of 20w = 75w

Mid 20w thru mid 30w = 80w

Mid 30w thru low 40w = 85w

Low 40w thru 50w = 90w

60w up = 140w

1550vt · #7 09-20-2009, 07:40 AM

I agree that the viscosity ratings cannot be compared and just saying that motor oil is too thin may not have been the correct thing to say. I think we can all agree though that gear oils are blended and have additives suited for a specific purpose other than motor oil blends. Motor oil may work just fine in the transmission and I know some aftermarket manufacturers recommend it as well as lubricant manufacturers. I just found it a little strange that the MOCO is still putting the syn 3 in all three holes. I thought they had drifted away from that. I know some dealers are now using this Formula Plus.

prodrag1320 · #8 09-20-2009, 11:35 AM

I always,right from the start,dissagreed with putting ANY 20/50 in a transmission,never would do it in my shop
kirby
www.veetwinperformance.com

big cahuna · #9 09-21-2009, 08:49 PM

I run 20/50 wt gl1 rated oil in my heavy '03 ultra classic trans. Have been doin so since it was new. It gets used thru the summer in temps up to 100 degrees, and thru out the winter in temps down to 15 degrees. So whats gonna happen and when?.,,

Notgrownup · #10 09-21-2009, 08:59 PM

I used 20/50 in all 3 holes unti 30k miles then i put severe gear 75w140 i think in the trnny...smooth it out a bit but still use aMSOIL or Mobil 1 in the primary. Lot's of opinions here...most are good opinions...Nobody has stear me way off track yet.