I use regular gear oil 75W90. I change it every other oil change, which is about every 6,000 miles since I change my oil at 3,000 intervals.
Mike, your only getting 2300 to 2800 miles from a rear tire, what kind of tire are you running? I got 5500 from my stock rear and only changed it because I was going on a 3,000 mile trip and didn't want to push it. My rear 023 has 6,000 miles on it and is no where near the wear bars.
I run the 190/55 PR2. And I ride 95% of my milage is on extreme twisty roads.
I don't ride my C-14 like most of the other curmudgeon forum members...
I have a garage full of sportbikes and I use my C-14 in the same manor as I would use a sportbike.
See my crash thread.
Back to topic.
It is actually fun to be condosending on a forum.
Too many of the old farts on this site take life to seriously... They need to lighten up.
If I can ruffle the feathers on their thin shin then I can I smile and chuckle a bit each day.
For God's sake it is the internet and everyone has an opinion and everyone seems to think their opinion is the best for everyone's location.
Yes, while I have the wheel off, I change the final drive oil.
I did the same with my K1200LT. It is a minor cost which can help prolong the drive.
However, I have seen a lot of C-14 riders visiting my neighborhood, and you know who you are...
You guys could go 100K miles on the final drive oil with out changing it... Try riding the speed limit.
I know the C-14 can break 35MPH.