Couple of observations... My ST1300 is a 2010 I bought new. It now has 2094 miles on it. I changed the oil a few weeks ago. I had been mulling over the final drive oil and decided to do it today.
First let me say, Joe's explanation is terrific. Had he not mentioned the need to clean the magnetic area of the drain bolt, I would probably have wiped it off and not noticed it had crud inside. There was a lot of particles/crud attached to the magnet... Meaning, the recessed area of the drain bolt was packed to the top. I also noticed the drive oil was dark grey and seemed 'heavy' or 'laden' with crud. So, I think I changed it at a good time. I used a mineral hypoid gear oil with a weight of 80w90 as the service manual says. I used the tube approach Joe called out and it went in quite smoothly. Another observation is that while I can't be sure as I didn't do measurements, it seemed like I put in more oil than drained out into my pan. I looked inside with a flashlight before and after and there appeared to be oil to the top of the reservoir before. And, I kept adding until the oil started to flow out. So, I did as the manual and this discussion states. It just seemed like more oil went in than came out.
It feels good to have learned these two simple basics about my bike. Now, I will try to learn how to change the clutch and brake fluids. But, those are a little scary to me because I just don't want to mess it up! If there's anyone in the Glendale Az area who is knowledgeable and would consider supervising me while I do that one day in the future, I'd definitely pay for the pizza and drinks.
Thanks, Jerry