Thanks - You're spot on as she never gets out of 3rd gear and does less than 2K a year! In fact, after looking at how clean the oil etc is, he won't bother to do a full service - he'll just thrash it down the local dual carriageway and back a couple of times. Mind you, for such a tiny little engine, it goes like a little rocket when given the chance!

Thanks again!

Also it's possible that the continuous short journeys with a cold engine have taken their toll and the piston rings are carboned. This will lead to crankcase compression and consequently oil in the air filter. You could try using a oil flush immediately prior to changing the engine oil and filter, and see if that helps. If it doesn't you have two choices. Either an engine overhaul or live with it.

Short journeys are very bad for your engine's health....