Mine is the same, the oil is travelling up the intake pipe too. glad i seen this thread, was a little worried

never cleaned mine out (next job)
When you take the pipe off where it goes onto the block, should there be a gauze filter in there because if i pull that pipe off whilst the engine is at idle a lot of oil splashes out.
Just a thought but gauze could have stopped this if it was fitted from new

and its now rotted away, been stolen

, dissapeared
Also do catch tanks have to be removed for the MOT
