Barry, If that is your only issue with your TO-30, you likely do need a rebuild.
When you say carries 10 psi, is that hot pressure, and at idle or full speed? Big differences there.
When we get into talking about oil grades, pressures, etc. you will see a wide range of opinions here. Follow the advise that you feel best fits your situation. Having said that, I totally agree with Jim, low pressure is not necessarily a severe problem. Flow is important, but we have no way to measure flow, pressure is our only indicator, but that's not really the same thing. I doubt the old timer did any damage by adding gas to the crankcase, probably just cleaned it out REAL good. As the other guys reported, I have done the same in my old Pontiac, add kerosene to the crankcase, run it to heat it up and drain it to clean out the crud. I ran a can of that "crankcase flush" stuff thru my TO when I first got it. From what I could see, it looked and smelled like it was just kerosene.
My TO ran for years with ~10-15 PSI oil pressure at working speed with 30 WT oil. It had always burned oil real bad, but when I saw oil in the radiator, that was the last straw. I saw no measurable damage due to low oil pressure. In fact my crank and cam were right on tolerence. But, my oil pump was shot and the pump relief valve was seriously eroded out, causing my low pressure. If you tear into your TO, rebuild the oil pump first (~$45 or and fairly easy). The oil pump will over-pump your normal engine requirements, so a good pump will compensate for some wear in your crank journals, etc. If you rebuild your pump and run 30wt oil, and your still worried about pressure, then you can tear into your crankshaft bearings if you want. I don't recommend switching to 50 wt oil or whatever to try to get your pressure up, flow is more important, use the right oil and take the pressure it gives you. 30 weight non-detergent oil was the oil spec'ed for your TO back in 1952-3. The problem with straight 30 weight oil is it is thick and start-up, then thins as it gets hot. A modern multi-weight oil will provide more consistent viscosity, thus pressure, across the whole temperature range. Since the old timer pretty much flushed out your oil system for you, I see no reason not to go ahead and switch to a good multi-weight detergent oil, like a 15W40 commercial grade diesel oil, or similar. I run 10W40 in my TO, but gave it a total rebuild several years ago, it holds 25-30 PSI from idle to full speed. I also want to make sure my original 6V TO will start for me on those cooold Winter days, so I stick with the 10W40. The 10W grade oils tend to be more like 10W oil with modifiers in it to make it act more like a 40W viscosity at operating temps. The 15W or 20W oils tend to be a higher viscosity base oil.
George
