high pitch noise coming from oil line
Have you ever cleaned the screen in the pump? There are a series of bolts, radially arranged, that hold the end plate on the pump. There is a screen right inside there that catches the larger muck. If this has never been cleaned, it could be acting like a restriction, making the high pitch noise. Also, make sure that your tank valve is fully open. If it was partly closed, it can also make that noise. When you think of high pitched noises in pipework of any sort, you generally are looking for a restriction. If this oil line runs across the basement floor, has it been pinched anywhere? Just some ideas....