What is dry?

dry compression test

Glossary “dry compression test” Definition:
A test to determine engine compression. After the engine has reached operating temperature, remove all spark plugs, disable fuel and ignition systems, prop open the throttle, install the compression tester into the spark plug hole. Crank the engine at least five compression strokes and record the reading. Repeat these step for the remaining cylinders. Compression readings are considered to be within specification if the lowest reading is within 75% of the highest reading. When performed on a diesel engine, use a compression gauge designed for diesel engines.. Compression gauge is attached through the glow plug hole.