oil smell worcester boiler

[vonspritz]

The smell of oil (not an exhaust smell) appears after the central heating has turned off. Sometimes it's worse than others. There's no leak that can be seen, I've had several boiler experts to have a look at it & have so far had a new pump & other parts fitted and a set up which involved various hi-tech measuring devices. One guy suggested that the wind direction might have an effect, but it seems to happen whether it's windy or not. I'm getting desperate as the cost is adding up and it will soon have been cheaper to buy a new boiler.
Please advise
Vonspritz

 

[Burnerman]

A kerosene pong?
Check the on / off tap inside the boiler casing, these often leak.
Replace the flexible pipe that goes from this on / off tap to the burner pump...these should be regularly replaced as a matter of course.
John