I bought 2x 1ltr bottles, used a brush to do all the chassis members, all the inside skin I could get to and loosened the fuel tank moved it out the way to do the back skin also all the fuel tank and then used a garden mister to spray it in any orifice I could find. Had a full tin left over and about half of the one I opened, it's very thin almost water consistency and spreads well but does take a couple of weeks befor its dried enough not to just wipe off when you touch it. Now it's been on the road for 5 months I'm just about to give it another good spray with a garden mister to make sure it's all been got. Just don't forget to rinse the mister out when you've done its cleans easy, but maybe buy a new one before you spray your tomatoes etc, not sure dinitrol tastes so good
I'm also going to give the bottom skins (under seats) a good layer of underseal next week, along with inside the wings to try an reduce stones leaving the star marks on the top surface, after that I'm hoping to drive the tyres off it this year