Should the oil gauge show a low reading when idling but go up to a decent reading when driving?
No, but it is a common fault so I wouldnt be surprised. Mine does that, as did my last FD.
Cheers
Lee
Err it should show lower when idling than when driving else yu have a problem some where. (once the engine is properly warmed up that is).
Mine reads 4 on idling when the engine is ready for a blast.
mine sites about 2 when idling when warm, 4 when cold.