Kawasaki engineers determine the correct change interval based on oil protection and cost of ownership. There is no WAY they would recommend an oil change interval that is harming the engine, no way. Why, because of a warranty and because in this great country if people discovered that an mfg was recommending an oil change interval that caused excessive wear and tear they would sue the crap out of that company and win millions of dollars. The amount of oil is immaterial, the engine is ONLY a 650, it is a tiny motor, despite how it may look on the outside. Think about your car engine, 3, 4 or 5 liter engines, that is 3000, 4000 or 5000cc engines hold "only" 5 quarts of oil or LESS in modern cars and most come with oil life monitors that call for changes anywhere from 7500 to 10000 miles. Hell my BMW called for oil changes every 15k.
Sure, the oil doesn't go through a tranny and the engines do not rev as high, but on the flip side cars run hotter, idle more, sit in more stop and go traffic which is 1000000 times worse for oil.
Think about that for a moment and then also consider that you can get up to 5 years UNLIMITED mileage warranty for your bike for a few hundred dollars. Do you really think Kawasaki would put all this risk to save the consumer a few dollars in oil change costs?
If you doubt this, go take a sample of your oil at the 5k mark and send it to a lab for testing. For a few bucks they will tell you how well the oil is protecting your engine and a lot of other useful information. You cannot go by the color of your oil and assume because it is dark it is not protecting your engine.
That being said most people change their oil way too often for peace of mind and their own comfort. Nothing wrong with that at all, but IMHO a 2500 mile oil change interval, unless that is all you have ridden in a year is a waste of money, while it is only a few bucks, it is still tossing money away when a longer interval provide the exact same protection.
Now you will read people state the bike shifts smoother or runs cooler or even sounds different with fresh oil, and that may or may not be so, but the fact is, if you change your oil every 5k or at least once at the end of the season, which ever comes first you are doing no less harm to your bike than if you changed it every 2k.
Last edited by marc11; 06-21-2010 at 08:16 AM.