Yes I agree, I think you're trying to resolve a problem that's not there. However if there are no valve seals and if that oil level in No.4 is abnormally high perhaps it can feed oil down the intake valve guide. I'd be looking for other reasons for the plug fouling, fuel, spark or sparkplug heat range. If its burning enough oil to foul the plugs in a short period of time then there'd be a lot of blue smoke.