HI I'm new to this site and would like to say hello.

also I'm looking at a 02 GTX 4 tec it has 150 hrs is in reasonable condition for age. My question is, In the bottom of the hull is a mild film of oil ( not sludge ) you can still see the fibreglass through it but it is used engine oil, is this normal or do I need to search further? I could not see any oil over the motor. Could this be spill from oil changes? Also what else do I need to look out for on this model?
Thanks for any help