Nothing scientific about the plane repairs, but trip was science mecca

The trip was off to a good start. Made good time to the Pittsburgh airport, narrowly missing the 100,000 people the shuttle driver said would be converging on the airport to see the Air Force Air Show at 1 p.m. Whew!
A slight glitch arose as we sat on the airplane awaiting take off. The pilot announced they had found a small “anomaly” in the pre-flight check and mechanics would arrive shortly to check it out.
Minutes after the pilot’s announcement, a U-Haul van (with RENT ME! $19.95 PER DAY IN TOWN emblazoned across the side) pulled up to the plane. Out jumped two guys wearing removable “Jet Care” armbands. They puttered under the plane for a while, then came out carrying a few dirty rags and threw them into the van.
Just a few quarts. Next, the pilot announced the left engine was a little low on oil, so they would just add a bit while they were there. Noticing one of the guys fooling around with his tool belt below my window, I took a closer look