1994 mustang v6. I performed a compression test today. 5 out of 6 read 125lbs. #1 read 105lbs. Doesnt burn any oil or blow smoke. How much should a guy be worried about the difference. Thanks.
Squirt a little light oil into the #1 cylinder and repeat the test. If the compression comes up, you're getting ring blow-by. If there is no change, your valves are the cause for the low compression. Once you know the source you can go from there.