Re: low compression?
Valves that don't seat properly will give poor compression. It's generally a carbon build up issue, or worst case is metal distortion from excessive heat in which case will require a good amount of elbow grease to get the job fixed up. Worst case would be bad piston rings as mentioned above - only fix is to take the block apart (expensive and timely repair to do, even if you do it yourself)
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!