Installed Spectro 6 today in tranny, normal routine for me is to change tranny fluid every 5,000 miles, any suggestions on how often to change Spectro?
I had the same questions you had when I started sifting through posts to educate myself. Just like the replies you got, there are no really hard and fast rules in my opinion, except: using a quality synthetic lubricant is better on every level for playing the odds on keeping your ride healthy for a long time.
As far as frequency, some go by milage, some by time. If you don't put that many miles on, and lay the bike up for a long winter, change the fluids before storing the bike. Some work multiple fluid changes in for timing, ease or just routinely giveing you bike a good "look over" while the fluids are draining etc.
For me, I change the motor oil every ~3k (3's, 6's and 9's on the odometer) and the chain case and trans every 10K. But that is my riding style. Lots of highway with planned stops and starts. I have the original front tire with 34,000 miles on it and there is still plenty of tread left, so you can see I am pretty easy on wear. (My car has 130K and the original brakes, again, mostly highway, very little shifting, very little braking). I change the brake fluid and my shock oil once a year. Again, it is my money and the work is easy. Aside from the cost and the small potential for perhaps stripping a bolt (torque wrench!!) or some similar mishap during the fluid changes, there is no way I am going to believe that changing a fluid out "early" is ever bad.
Motor oil get beat up and cooked worse than all the other fluids, so 3-5K miles seems to be about the average. The rest have a pretty wide range.
(Every time I change the Specto, it looks brand new to me. Never any metal on the plug. Can't say that was true when I first got my Ultra when it had HD Syn 3
everywhere.