Thats interesting, and very handy! Mine is, as you can see, completely different which makes oil checking and filling much more difficult. So far i think the 2 options are as 7 Wonders has suggested to cut an inspection window in it, but this is on the assumption that i can remove the cap with it in place (Which admittedly ive not attempted yet), or alternatively to cut the tongue wide enough to access the whole cap in a large U shape.