At costco, 15w-40 runs $25 for 24 quarts, we run it on all our vehicles,save the 64 dautsun and the boat which get a single weight oil. (also $25 for 24 quarts at costco)I run rotella in everything else though, in my amigo I run the t6 synthetic, and all the diesel engines save for my dad's 6.0 (which gets its oil changed by ford) gets the standard 15w40.