Hi all,

I'm in the process of changing oils on a '99 Road King Classic. I'm going to the Mobil 1 V-Twin 20W-50 for the engine (with H-D filter), Mobil 1 75W-90 Synthetic in the tranny, and I'm indecisive about the primary. I intially thought the Mobil 1 V-Twin 20W-50 but then I read some other posts about 10W-40. If I were to put any other Mobil product in (other than the V-Twin 20W-50), should it be the 'other' 10W-40 'For Motorcycles' or just plain old Mobil 1 sythetic 10W-40? Another one on the primary - I've never changed the primary oil before, is the drain the 'odd' headed screw on the side of the case (near the bottom)?

Thanks in advance,

Bob

 

The only concern I'd have with the automotive Mobil 1 10w-40 would be the amount of molybdenum. The moly is a friction modifier and too much will mess up your clutch. The muttersickle version is made for wet clutch use and it will work. I didn't have the car version analyzed, so I don't know what's in it.

 

Hey Skip, have you ever heard of putting some of the posi-trac additive in with automotive motor oil in a pinch? Apparently it has some additives to allow the posi-trac clutch plates to get some grip...
I wouldn't want to do it, but in a pinch it might get you by...

 

Never heard of that. Must be similar to the old brake fluid in the auto tranny trick. Hmm, if the plates are already toast, couldn't hurt anything and might get you home.

 

I did exactly what you are doing for oils. I used the 10w-40 motorcycle oil in the primary. As for the drain screw I dont know, Ive got a softail and my drain is a torx head under the primary near the rear.

 

So, can you use the 20w50 in the primary, or 10w40? The owners manual dosn't state.....


joe

 

Just my .02 here. I switched back to the HD primary oil from the Syn 3 that came in the bike. I know that this oil has been working well for all eternity and there are no friction modifiers or such in it , besides it's less expensive than any of the synthetics, but that's not the reason I chose it. Just like to take all the guess work and hoping out of everything.

Also for those of you that have that allen or torx drain plug in your primary cover, a word of caution here.

Pay particular attention to how far you insert it into the cover as the magnet on the end can contact the clutch basket and make a real problem in there with bits and pieces. Some teflon tape or the thread sealer will allow you to set it at a height slightly above the surface and not cause a problem for you.

 

Should be the same. #27 Torx. Same size as the screws on the Derby cover.

 

Very good advise.... If you dont stop turning the screw it will probably go all the way through.
I changed oils again the other day to (Engine, Mobile 1- 20-50syn) (Primary, Mobile 1- 20-50syn) (Transmission, Mobile 1- 75-90syn)
Seems to have quieted all mechanical components down a little.