What product for wood trailer deck?

I've recently picked up a 10x6 utility trailer that has 2x6 boards on the deck.  Its a few years old and I'd like to coat it with something to help it last a while.  What have you guys had good luck with?

Bed liner material sheds water and adds some grip.  I wonder how that Flex-Seal stuff would work.

Old motor oil

gsettle said:

Old motor oil

Literally this.  Used to mix motor oil and diesel in a pump sprayer and spray down the decks of all our hay racks 1x a year.  They sat outside year round and we really never had a lot of issues wiht them.

Good wood helps too.  Use oak if you can afford it.  

Used motor oil sounds interesting.  But I'm not sure that's what I want to use.  Is it going to stain my jeans if I need to kneel on the deck or make the tires of whatever I'm hauling a little extra slick?   I like the grassroots suggestion, but I think I'm looking more for a sealer or product off the shelf at a big box store - something that will be completely dry in 48 hours or so.  

Behr Red Wood Deck Stain. It's iron oxide red like an old Ferrari, it's oil-based, it lasts, and it's $15 per gallon. 

I'd probably use something like Thompson's Water Seal. 

Porch and deck enamel from Lowes worked great on my trailer.

If you need to replace boards, try to use "soil contact" pressure treated lumber. (The lower grade pressure treated stuff is crap)

Rog

I used black Rust-o-leum paint, rolled on with some of that traction grit stuff. It's oil-based, so it pairs well with my pine decking. It seems to last about 10 years before it starts peeling.