white oil inside oil filler cap

hi guys i have white oil inside my oil filler cap
the bike runs well oil in engine and site glass
perfect no white,my bike is a z750e 1981
just wondered whats causing this cheers dave

That is water condensation in the oil. That can happen if the days (or nights) are very humid. It can also happen if a Hygroscopic substance gets introduced into the oil, such as alcohol, acetone or some additives. This "creamy white" sludge can collect in many parts of the engine just like it is on the oil fill cap usually on horizontal upper surfaces. I would flush the engine with a engine flush additive and change the oil.

thanks otakar will go out and flush oil and change
nothing to worry about then cheers

And when changing the oil, it's best imo done immediately after the engine is shut down after having been run long enough to attain normal operating temperature.

This helps flush more contaminants from the system while they still remain suspended in the oil.

Sometimes the entire crankcase oil supply will appear "light milky chocolate" color or "coffee with cream" color, due to moisture absorption into the oil.

Good Fortune!

thanks guys something else for my misses to say now whats
wrong with it
i always reply nothing happy days

Just say "Nothing honey just changing the oil" :laugh:

It always happens in the winter if you ride. If you've ridden this winter in cooler weather for short distances I wouldn't even bother to change oil as it will be fine once the weather warms up for more riding. Changing oil never hurts of course though.