Have several questions on refinishing my truck bed, but first the caveats.
This is my workhorse. It sits outside in the Texas sun, rain, tree sap, whatever. I use it to haul all kinds of crap including greasy nasty used auto parts (may throw down a tarp for the worst cases). So I'm not looking for show finish, and I have no intention of dissassembly. Just want to clean it up and protect it. I think it is oak, and has been in place for many years. Has some splitting and as you can see, lots of black places.
Has many dry spots where the finish appears to have failed.
1. Can I scrub it with something like scotch pads that won't scar the steel strips?
2. Can I bleach out some of the black - it looks like some kind of fungi.
3. What is the pure toughest clear finish I can apply?

Right now its worn weathered look fits in with the rest of the truck, I just don't want it to get worse.

Thanks.