I'm planning on doing a bit of traveling and as rule of thumb, no matter what the situation be, i always plan for the absolute worst. I've been using HD sport-trans primary fluid in my 97' xlh 1200 but i'm afraid i may not be able to get it everywhere i go. I dont want to carry any with me (i say the lighter you pack, the better) so does anyone know what the weight/viscosity rating the sport-trans fluid is? can i substitute it with a synthetic/mineral engine oil for the rest of the bikes life with no problems? (preferably synthetic, i'm already running Valvoline 20w-50 full synthetic in the engine) I've done a bunch of searches on this forum along w/ another one at www.xlforum.com and the closest i can get is that 10w-40 oil is a good substitute but nobody had run it for longer than 500 miles or so. Has anyone had any experience using straight engine oil for the primary?

 

Synthetic oil that you put in the engine should work fine in the tranny/primary. There is debate about whether this is a good idea or not. Some say no problem, others say it's best to use gear oil and tranny damage has resulted. I think markcuda (former member) ran synthetic oil in his tranny and got 170K out of his motor before it died. I'm not sure about the condition of the tranny, but it didn't fail as far as I know (You may want to confirm this). In an emergency that is what I would use if gear oil wasn't available.

 

Engine oil in the engine and gear oil in the trans regardless of what any body else has used. Just because someone else has used engine oil doesn't make it OK to use it in the transmission.

 

20-50w synthetic MOTORCYCLE motor oil is the best to use in the Primary/transmission. Some people will use a slightly heavier 75/90 transmission fluid. All "sport-trans" fluid is, is cheap dino motor oil. Your better off running 20-50w full synthetic permanently.

 

I run the 75/90, mainly cuz it can get so darn hot here in Phoenix (although not at the moment!). Do agree on the 20w50 syn, though. Smoother, quieter shifting and less chain whine are the rewards vs. the MoCo's oil...

 

Some synthetic motor oils are not recommended to be used in the primary/transmission.

The only one I know of that says its ok to use the same oil in both is AMSOIL.

 

Two things: One, old HD Sporties ran the same primary/tranny oil as engine oil for years and years, so running the same oil in yours ain't likely to hurt. Two, engine oil viscosity and gear oil viscosity are measured using different "scales", if you will. They do not directly correlate with each other. As a result, 75w-90 gear oil is the same "real" viscosity as 10w-50 engine oil. 75w-140 gear oil is the same "real" viscosity as 10w-60+ engine oil.

 

If its 20-50w oil, it can be used, whether Amsoil,Synth 3,Redline,Royal purple, Mobile 1, etc etc etc.

 

Would i be able to switch from valvoline full synth 20w-50 to mobil 1 15w-50 extended service synthetic w/out too much trouble? would the valvoline 20w-50 full synth or mobil1 15w-50 synthetic be able to be used in the primary for the life of the bike?

 

Any 15-50, 20-50 synthetic motorcycle oil can be used in the primary/transmission FULL TIME, for the entire life of the bike.