Originally Posted by
megan
Radial engines leak oil, during military training it was said, tongue in cheek, if you could step over the puddle of oil on the ground it was only a drip. See some operators at at air shows have reused tins from the kitchen to hang below the known leak points to collect the drips and prevent fouling the tarmac. In the hangars you will see drip trays on the floor adroitly positioned.
Indeed, see here from 'our' C-47; drip trays were always put in place directly after flight, followed by a board to protect the tyres when the tray filled up, then handy rags when it all cascaded down the boards... all quite normal:
From this it's possible to see that if the underside of the Stearman hadn't been wiped down recently a bit of oil may not have attracted much attention (disclaimer: conversational comment only, I've never flown a Stearman, nor am I familiar with this operation, who may religiously clean their a/c after each flight!):