bubbles seen through engine oil level window...
 

Hi,

I've just noticed what appear to be air bubbles/froth on the top of the engine oil as seen through the level window when the bike has run through city traffic for about 40mins. Is this normal, or does it suggest a fault/the need to drain the oil and apply new oil and a filter?

I've only had the bike (a 2005 sv650s) for a few weeks now. I picked it up with under 2k miles.

When I bought it, the shop had done an MOT and put in new oil/filter. I assume they used 10w40 semi synthetic. A friend of mine had added a small (read 200ml or less) of his 10w50 full synthetic oil at the tail end of my only long ride. My understanding is that that is not an issue and the two viscosities/blends will mix. Or am I wrong and this is possibly the issue?

Thanks,
Ken

Re: bubbles seen through engine oil level window...
 

i think its just wee bits of moisture in the oil that rise to the top when it gets hot, mine has a white layer ontop of it quite frequently but i dnt think its anything to worry about!

Re: bubbles seen through engine oil level window...
 

Great - thanks.

Re: bubbles seen through engine oil level window...
 

I would not mix full synth and semi.

But a little froth is not a worry, the engine parts tend to churn oil up a bit, it does not just sit there in the sump doing nothing.

Excess froth can be caused by the oil level being too high, this can cause problems. Where is the level when checked cold with the bike vertical?

Re: bubbles seen through engine oil level window...
 

Oil gets aerated during normal engine running. Some large bubbles on the surface is perfectly normal, as is some visible aeration of the bulk oil.

When developing engines, tests are done to measure aeration levels as part of the normal development process, determination of maximum and minimum fill levels etc. There are a number of ways of measuring aeration of oil, and different engines will have different tolerance to aeration.

Providing you can see the oil at the correct level (engine stopped and allow to drain down for a minute or two, hold bike upright) then there's nothing to worry about.

Re: bubbles seen through engine oil level window...
 

What about the mixing of full synth and semi? I'm not too sure about that one.

Re: bubbles seen through engine oil level window...
 

I can only go on what I've read to be honest, and the oil companies say there's no harm in it. As a rule I don't like mixing oils, but to be honest I'm sure it's pretty unimportant. If it caused any significant problems there'd be engines dropping dead all over the place!

Re: bubbles seen through engine oil level window...
 

all this bubble talk is making me crave an aero...