With more and more "high mileage" synthetic lubricants coming out for your motorcycle - and automobile - I have a question to ask.  I have heard some people say the synthetic lube will not break down and you can run it up to twice as long as motor oil in your bike.

My question is, doesn't it still get dirty?  And doesn't that mean your oil filter will get dirty and not allow the required circulation?

My experiance is that the new fuel is cleaner and leaves very little carbon, the engines run cleaner (leaner) and the fit of rings and bearings is closer reducing cylinder leakage and crankcase pollution of lube oil. The oils don't break down as fast and will tollerate higher temperatures causeing less oil tars. The oils do get dirty but it takes longer and is not as bad as older generation lube oils. My bike has a common engine and gearbox sump lube system so clutch wear is also fouling the oil. I seldom do short trips so cold condensation contamination of the oil is not a problem. ( Last trip to the grocery 2 blocks away took 30 miles and a cup of coffee could be 70.) I change the oil at 7500 miles or fall prestorage. The AMSOIL still is clear for the application and the filter is changed with the oil..

The Suzuki C90 engine is oil cooled by oil spray nossels in the engine and transmission that are high pressure small orficises.  No problems have been heard of by filter plugging or nossel plugs..Service calls for 3500 miles or 6 months for oil (5-30 petrolium) and 10,000 oil filter change..

I have been running Amsoil in our bikes since I have had them (Harleys) I personally change my oils once a year in the fall. I average around 15K a year. I change my filter every 5K. I have 60K on my road king. My bike stays cool and have NEVER got it close to over heating.
www.amsoil.com/products/streetbikes/WhitePaper.aspx ;

My buddy who sells Amsoil also told me I could run over 10k on it. I was skeptical at first, but have had no problems. I change the filter at 5,000 or so and even when I drain the oil at 10,000 it still looks new.

There was a 3 part series in one of the motorcycle magazine gear towards Harley (email me if you want the name of the magazine) just on Oil in twin cams and Evo engines. In it they tried to address that issue. The short and sweet it was it still gets dirty and to change the oil and filter at the recommended service intervals (5000 miles) for Harley’s.
Take it for what it’s worth.

Synthetic base stock is much purer and cleaner than Dino oil, so they can use better additives. Factor in what Hgsc90 said above and you will get longer life from your oil, But yes, it still gets dirty.

For me it is not worth the little money savings to push it too long. I use Amsoil and change oil and filter every 5k. But then again I had a trip this summer were I went 8500 miles in three weeks and was not at all concerned about changing it until I got back. It still looked clean. I am figuring my motor to go 200k without problems.

Here is a link to a site all about Cycle Oil or most anything else. Has alot of great info.

http://www.webbikeworld.com/motorcycle-oil/