I had something like this happen with my Rapide. After a full winter of sitting, the oil in the tank wasn't visible, which could mean its down a quart, or a lot more. I didn't bother dipping to check, instead assumed there was a lot of oil in the sump. I removed the drain plug but only a small amount of oil came out.
With the plug back in the sump I added enough oil to the tank to bring the level up to where it should be.
That took two quarts, which seemed a lot as I don't usually let it get that low.
On start up I had oil everywhere as the sump pumped out and the tank overflowed.
I guess there was a hydraulic suction lock happening when trying to drain the thick cold oil from the sump. Kind of like an inverted ketchup bottle that won't flow until you give it a wallop on the side.
Glen