A strange on going issue. I have a 292 that I rebuilt several years ago. It runs great, but every year when the temperature drops, my oil pressure goes nuts. When cold ,when fired up, a steady 50lbs. As it starts to warm and I start to drive, the mechanical guage ( 4th one) will start to slam up to 80-100 psi. When it gets up to temp, it settles down to a steady 40-55 lbs. I run 10-30 oil, and have checked the relief valve in the gear type pump. This has gone on for years and have never blown out a filter or anything, but it does have me scratching my head at this time of year.( temp in the 40s). Hmmm

I'm with Ted, don't run below 40w. The old engines have the clearances that like thicker oils. Oil technology has moved on so much in 60 years with multi grade oils and what Ford recommended back then was the compromise that was made with mono grade oil. It is still a compromise now just not as much, as the perfect oil would not change viscosity when the temperature changed. I run 20w-60 but we never see freezing here and that particular oil has 1610ppm zinc content. If it got colder here I would run an oil with a lower starting number. Remember even when it is below freezing in winter over there, that oil with a low end number is still extremely thin when your up to running temp at 180F.

You are correct that the FORD recommendation was mono or MM Grade oil, however after running "Y"'s hard on short tracks I remmember that the guys running thick oil seemed to squeeze and burn the bearings out and soon there after a rod where as with 30W we Did not lose engine one in the six years thay I ran them before going to FE's with the Later Model Body Styles, But as they Say "To each His own"

Tom

What?