In Reply to: Oil pressure and tune up posted by Theo Morris on July 25, 2018 at 15:24:22:
Oil pressure varies with engine condition. At 1500 RPM a good tight engine will produce 40+ PSI at cold startup and hold 30+ when hot. A worn engine will produce similar cold pressure but it will fall to 10 PSI or lower when hot. Anything in between is generally acceptable. Less the 10 PSI hot is a sign things are getting pretty worn.
The original oil specification was for mono-grade oil to be changed with the seasons - SAE 20 in the summer and SAE 10W in the winter. A modern all season SAE 10W30 is more than acceptable and avoids the need for seasonal changes.
The original hydraulic oil specification was for mild EP SAE 90 gear oil in the summer and SAE 80 in the winter. A modern UTF is a close match for that and will provide year round service and no need to change on a seasonal basis.