Oil Change Interval

Hi Tapio,
The color of your oil is not an indicator of its lubrication properties. When fossil fuels burn they produce carbon and that's all you are seeing is the oil doing its job in removing carbon and other contaminates. The only way to tell how an oil is doing would be testing which in most cases more expensive than just changing oil at a regular interval. Most I know change oil with 100LL at 25 hrs. and 50 hrs. using auto fuel. If you can get Aero Shell Sport Plus 4 I would stick with that even if it cost a tad more. It was tested and formulated just for the Rotax over years and thousands of hours of use. If you can't get it then use a good motorcycle oil with a reasonably high ZDDP additive package. If one oil you pick only has let's say 1000 ppm of ZDDP and the other 1500 ppm ZDDP then use the 1500 ppm motorcycle oil. Do not use a car oil and do not use a full synthetic with 100LL. The full synthetic will not suspend the lead. Changing oil at 25 hrs. with auto fuel is just a waste of your money. 50 hrs. is more than on the safe side. Some people do use their oil longer than 50 hrs. I'm personally not a fan of this and I don't personally know of anyone that does this.

My 2 cents:
I look at oil in our engine as its blood. If you disease the blood, just like a person they expire early in life. It's easy to keep the blood and the engine in good health. In the long run it's usually cheaper to keep the engine maintained to a good standard than to pay all the money later due to early wear.

Here is an older oil comparison article that may help answer some questions. It's published by Amsoil, but a good educational read:

http://www.oil-tech.com/amsoil-pdf-files/motorcycle-oil-comparison.pdf

Roger - Is it still best to do the oil change at 25 hours now that Rotax as openly stated 50 hours?

Bob