hi everyone just bought a golf mk4 gti 1.8, 125, 5 door.

problem i have is when driving about for about 1 hour the oil red light comes up and beeps every now and then,
i have just bought a compression tester, does anyone know what the correct compression should be for my model
or any other advice on what could be the problem, the seller told me he had changed the sump couple weeks back.
thanks.
reece