[cadillac_al3]

A loose spark plug willnot affect a compression test. Maybe when that tank of gas with oil is gone the next tank will run better.

 

[BC_Dan]

Leave the washer on the plugs. It's the gasket that seals the plug to the head.

The extra oil may be contributing a bit to starting issues, but only if the plugs are showing evidence of oil fouling.

 

[kccats]

This is why I always say to only premix a few gallons!
At this point just run what you have!