I switched to synthetic on the 600 mile service and I've been changing it at 7500 mile intervals.
The 4000rpm thing is for the break in, and Kawasaki uses the same for every bike, 4Krpm on a Vulcan or a ZX-6, they don't care. The maintenance part is bike specific, the intervals are good enough to keep the bikes from failing within warranty, so I figured that if they call for 7500 mile oil changes with dinosaur juice, I'm on the safe side using synthetic. Next weekend I'm doing the 22,500 mile service, it doesn't burn oil in between oil changes, and the sight glass is clean, so there is no sludge build up, but I'll be sure to post pictures of the valve train once I check them at 30,000 miles (if you hear the guys here, with 3,000 mile OCI and 10,000 mile valve adjustment, my bike should have blown up by then).
If you're in the US, or a country where you can have used oil analysis, then have your oil checked and figure out what is the proper interval. 3000 mile changes are a myth from the... 60s? Engines, fuels and oils are not quite the same as they were back then, and even oil companies are against 3,000 mile OCI.
Kawdog, don't bother, I don't care. You keep changing your oil every ride while you forge your own iron brake rotors.
Last edited by Süsser Tod; 04-07-2015 at 09:49 AM.