Motorcycle Safety & Driveability: Synthetic oil, kawasaki ninja, valve seals

Question
Hi William,
I have an '87 Kawasaki Ninja 1000R with 22,000 mi.
I have owned this bike since new, and has had excellent care and maint.
I have always used Castrol 20-50, but was wondering if I could switch to a synthetic at this point, without adverse effects. Would it be worth it to change now?
Thanks in advance,
Gary
Tampa, Fl

Answer
Gary,

Thanks for the question.

Since your bike is "relatively" old and has a good number of miles on it, I can't see any benefit to switching to synthetic oil at this point. And there may be some adverse effects. First of all, you may experience some clutch slippage uner heavy load and/or acceleration. This is simply because synthetic oil is "more slippery" than your Castrol 20-50. Also, you may find the oil seeping past gaskets and seals around the engine. Because of its increased ability to flow, it tends to do that. Lastly, you may notice an increase or appearance of smoke out the exhaust under load, during warm-up or just during regular riding. Synthetic oil can more easily slip past valve seals, piston rings, and other places regular oil cannot usually go, especially in a "mature" engine.

I understand the appeal of synthetic oil. It supposed to be better for your engine, and give better power, blah blah blah. Truth is, unless you are racing that old Ninja at the track, there is just no reason to use it, and several not too (above), besides the added expense. If you had been using synthetic since after your break-in period, that would be different, but since your engine has had a steady diet of 20-50 and has run without problems (at least you did not specify any), I'd stick with it, or maybe drop to Castrol 10-40 weight for a bit more flow in colder weather.

Save yourself the money spent on synthetic oil and spend it keeping your 1000R in top shape, it's a great older GT sportbike. You're coming up on a period where your bike will start to need things like new steering bearings, fork seals, maybe a new rear shock or fork springs. As long as you keep it tuned and the oil changed, there is no benefit to switching to synthetic oil.

Ride smart, have fun,

Bill Roberson