Trying to say out of this but can't. Change oil to viscosity recommended for that year of 350. It's 10 lbs per 1000 RPM.
@500 RPM that is 5 lbs......together with old mechanical gauge tolerance and gas thinned old oil, could look like zero. Don't worry about idle. Set idle RPM to spec. If it's a zero when driving at 30-40 MPH or it gets real hot, report back. I'm sure it's OK.
High oil pressure at cold start up is NOT normal. Indicates blockage/flow problems or wrong oil, dirty oil, thick oil or all that. After start up refer to above.
Last edited by bartamos; 04/28/2019 9:47 PM.
