Its been posted about a bazillion times on here. Just browse a little. Anyway......You need to add marine fuel stabilizer to the fuel but i always do it on the last trip out so that it actually runs though the fuel system and carbs, not just the tank. You need to add antifreeze. I do it with a submersible pump and bucket. I use the RV marine pink kind and pump it into the flush fitting while the engine is running. While that is going on, use fogging oil sprayed into the air intake. Then i pull out the spark plugs and spray fogging oil into the spark plug holes for 20 seconds. Replace plugs and crank motor a couple seconds. Then I change the pump oil. Then i cover it up and jack it up and put jack stands under the trailer to get the wheels off the ground. I do all this and it is kept in a heated garage....im kinda anal about it.