Oil down the sparkplug holes before comp test?

[deathpunk dan]

I've seen repeated mention of adding a tsp of oil to each cyl via the sparkplug holes prior to repeating a warm compression test. What type of oil is this referring to? Marvel Mystery? Brad Penn?

Also, I know the pelican article says to do the comp test with your foot to the floor for max airflow, and suggests failing to do so will result in inaccurate readings. The question is, how much difference does open or closed throttle compression test make in terms of increasing psi readings?

Plz explain.

-Some guy whose recent warm comp test revealed reasonably consistent but somewhat low psi #s...but he did not follow instructions and also wonders if finger-tight is good enough for the comp tester?

[HawgRyder]

If the first (dry) readings are taken....then a little standard engine oil is put in....and the numbers go up much higher...it tells you that the rings are the main problem.
If the numbers do NOT go up....it's probable the valves.
Bob

[911pcars]

For the amount of oil injected for a wet compression test (teaspoon?), use regular engine oil; nothing fancy (MMO or BP).

To confirm the wet/dry results, you can follow up with a leak down test for more concise leak location.

Sherwood