It's scary decades old, brittle fibreglass. It's just plain dangerous to use on the road. The idea of putting hot oil near gas in an old glas tank is stupid in the extreme. A hot oil tank in your crotch? Mmm, tasty!
It's worth about fifty bucks, and should be hung on the wall to look at, never to use and put lives at risk. I's not going to be your life in peril, so I guess you are O.K. with that?