Tim has a good point--maybe the oil pressure passage to the sender unit hole is partially clogged(maybe the synthetic oil loosened some crud up)and its not letting the full pressure get to the sending unit or gauge.Trying one of the other ports would give a better idea if this is the problem--some small blocks have a 1/8 inch pipe plug above the timing chain cover,another place to put a gauge(I think it might be the same oil passage that the sending unit in on,only at the other end of the motor--and there is a port on later small blocks near the oil filter--wouldnt hurt to check the pressure at theese locations and see if it reads differently.I've used a grease gun hose(clean out the grease first! /forums/images/graemlins/rotfl.gif)to hook up a mechanical gauge for test purposes,it has 1/8 pipe threads and will screw right into the block--easier than messing with tubing and ferrules.Might need a 1/8 pipe coupling to hook the gauge to it,depending on if its male or female thread. /forums/images/graemlins/crazy.gif
