Hi all. New here and looking for advice/ info on my oil pressure guage on the dash of my 80 series. Usually sits pretty low about a third of the way up but today after 30mins on the highway it shot right up to the top of the guage it was not gradual just shot up. Then back off the highway it went back down. Put some oil in and it was ok gor a little while then shot up again at 100ks. Dropped off the 80 or 90ks and it went down again. So im looking for peace of mind or advice. Thanks in advance.