Oil in the cylinder account for rings yes, but the compression coming up does not always mean rings need replaced.

Although 25 is really low.

Putting the oil in helps account for the fact that a compression test does not account for running conditions. Rings can expand with heat to bring compression up, also if the engine has oil squirters then that can't really be accounted for during dry cranking. Etc

While it points to rings, a cylinder leakdown test should be done to point to the exact problem

For the op. I was stating if all four plugs looked bad then a common piece probably fouled them. Check your coilpack.