Rookie question- from a rookie- how do I add hydro fluid 2010 s150?

[clydesdale]

I see the cap under the flip up grill in the back, but how the heck do I get it off? I twisted it, I pulled up on it and it won't come off. I have a real knack for breaking things, so I decided to stop and find out what the procedure is to get this cap off before I deploy my money costing strength to this cap. Thanks.

 

[Tazza]

It will lift off, it's rubber and can get a bit tight. Give it a little more of a tug, should pop out.