Detroits will burn a lot of oil running multi-weight. Straight SAE 30 is what they were designed for.
The saying for saltwater chevys is, you know they're out of oil when they stop leaking. Haven't met one that didn't mark it's territory constantly.
If it hasn't been started in a couple years, and double so if it's sitting outside, pull the valve cover and work the injector racks to make sure they're free. Have somebody stand next to the intake with a board to slam over and choke it out when you start it in case it decides to go to the moon. The emergency shutdown flap in the blower is usually froze or has been sucked through before and won't work when you need it. Even it does, don't use it for shutting the engine down under normal circumstances.
Otherwise, a jimmy was one of the best engine designs ever built. If you can stand the noise.
