Used to get a regular PAA DC7C daytime layover at my first aviation base. First order of business after chocks in was to put drip trays under all the engines and small collector trays that clipped on to some of the engine drains to keep the airport authority happy as they did not like the black gold all over their precious ramp. During the layover cleaners would wash down the upper wing surfaces behind the engines to remove the oil. There was even an oil slick on the tailplane from the inboard engines.
On start up later in the day the engines usually spat a good dollop of oil out the exhaust on to the wing straight away kinda ruining the cleaners efforts.
I once asked the PAA guys about the size of the oil tank on the R3350 turbo compounds and oil consumption and was told it held 56 gallons and that they didn't worry until consumption reached 4 gallons an hour. If it reached 6 gallons an hour with no obvious leak the engine was removed.