I tried to use the oil pressure wire and it didn't work. I think it has to do with the fact that every thing is low voltage. Use the sender with your gauges and all should be good. I deep sixed the original unit for the lt1 and put a direct pressure line in it's place. My harness was made for my 66 elky from a standard harness that excluded every thing I didn't need and had the computer programed for it.