Look at the Race Deck Free Flow XL, which is 18" x 18". It is thicker (3/4") than the regular Free Flow (1/2") and has flat ribs for (supposed) easier rolling of heavy objects. Race Deck gives Garage Journal members a great discount anytime and I love the look of Free Flow in pictures. I...
In my research, Ghostshield 8510 seems to be a great sealer to help prevent oil stains. Sounds like it won't change the appearance and requires just a good cleaning for prep.