I've been all around the houses with chain lube & I've found that a high end ceramic dry lube makes for the longest chain life while maintaining the efficiency of a new chain. The amount of lube you need is minimal when applied properly. I go through 2 120ml bottles/year, this is for recumbents which are about 250-280 links.
Yup... also use Ceramic lube and after gawd knows how many years of trying this or that lube.. ceramic the the best imvho.