my son was driving his truck the other day said it started running bad, did compression check first two cylinders had about 30psi of compression the other two had about 150 psi, wondering if it might be a head gasket or bad valves .i really dont want it be in the cylinders. the engine is not knocking. he said it sounded like the valves were making noise when it happend so he added oil just thought i might get some ideas before i tear it down

You can determine if it is the rings or the valves by putting some oil in the cylinder through the spark plug hole and re-doing the compression test. If the compression comes up to normal then it's the rings. If it doesn't come up to normal it's the valves. Low compression on 2 adjacent cylinders could mean the head gasket is blown. If that is the case you may have oil in the coolant or coolant in the oil. Put a pressure gauge on the radiator neck and if the indicator moves back and forth while the engine is running, you have a blown head gasket. Any radiator shop can check for combustion gas in the coolant, also.

thanks i appreciate your input ill try that