well i recently got this 95 ls with 219,000 miles. i know the owner and it was taken good care of, all highway miles. i decided to change the head gasket for extra insurance. so last night i did a compression test for the first time. my first readings were:
180-162-168-171. removed my shirt i forgot was draped over the air intake... 2nd run: 184-168-174-180. (not bad for such high mileage?). now it was the middle of the night, and for some reason i decided to add a little oil to each cylinder and run it again... 255-236-237-231. how can this be explained? i thought bad rings would cause readings after adding oil to go up to normal, not this high. did i add too much oil?

either way, i'm going to take it all apart now and attempt my first head gasket change.

Can anyone explain why it was so high?

i'll check back soon, thanks