I tried Endeavour Oil on my mahogany topsides. It was easy to apply but does require top up coats to maintain it. It looked OK at first but then went dull when successive top up coats were applied. I've now gone back to varnish brightwork. This is a lot more effort to maintain, but she's worth it! I'm not sure why you want to treat your decks. I have teak and I just scrub that with salt water. Burgess Woodsealer may be a cheaper substitute to apply to the deck?