Bruce in Bangkok wrote in
:

Years ago I was up in Oklahoma looking at an oil field. A mile square
and wells about 100 yards apart and pumping jacks on every one of
those wells powered by one single cylinder diesel engine running on
crude oil that drove the pumps by pull rods running all over the
field.


Put:
oil field diesel
into the YouTube search engine and you can watch them still running....lots
of them....