This is a '95 4runner 3.0: compression check on #4 (pulling one plug at a time) was 105. Number 6 was 155. I shot some WD-40 into #4 and that brought the compression up to 120. The vehicle had a valve job less than 10 thousand miles ago. The person that owns it wants to take it back to the person that did the valve job, but I think it is a ring problem. Could this still be a valve problem?