I have just fitted an oil pressure guage to my 83 505 SRDT and got the surprise of my life when at idle the pressure shot up to 60psi and during normal driving climbs to over 100psi. I expected that a turbo diesel would have good oil pressure but having mainly had experience with petrol motors prior am concerned that it may be excessive possibly due to a blocked releif valve. I have pulled this out, the one in the filterbase and it seems ok. If someone out there has any docs about when it should open or knows from experience at about what pressure these are meant to run hopefully it will be about what I am getting and there is no need to worry.