Re: oil cap rubs on hood/cracks
My first car was 1965 mustang. I went through two radiator hoses before I figured out I had a bad motor mount. On high revs the engine would lift up and the fan blade would cut through the hose.
To find out if the cap is hitting the hood I would put some plumbers putty on top of the cap. Close the hood and open it again to see if the putty is squished, or even stuck to the hood. If not, take the car for a ride with some healthy acceleration. Chech the putty again.