Low oil pressure

Apparently some people are not reading all the posts or not carefully. I recommended the 20w50 to TEST the engine and determine if it needs to be taken apart and inspected. Its an UNKNOWN engine so original owner might have drilled gallery plugs by timing chain, sloppy clearance, worn pump or who knows. By using a heavy oil, OP will be able to tell more about whats going on in engine without dis-assembly. If pressure goes to 20 at idle than we could assume wear or loose clearances, not spun bearing, drilled plugs etc. If nothing changes, I would think that it means there is a potential problem.

I would not recommend running 20w50 in a car parked outside in -10 weather, but I was also assuming the OP was not going to change his oil in a snow bank either. It would not harm his engine to swap oil and fire it up to check. If its garaged, it wont hurt it to keep it in there either.

So many people offered their opinion, like myself, but it seems there is no point to continue to share mine as several posters have stated I am wrong. Nobody that said anything against my theory answered any of the questions I asked, nor has Rusty(either one) said anything about the ridiculous statements they made. If you dont know what psi stands for should you even give an opinion? you are so sure that the engine is "fine" but have no info to back your opinion except a low pressure engine you own.

Just for fun, I went and started our 69 HT 318. It has over 170K and smokes a bit on start BUT has 20+ at idle and 60 at rev.

This thread was started to help make a decision about OP's engine. We can offer examples of what we have/had but stories of 400K hondas or cars run on synthetic do nothing to help OP make a difficult choice, run it and risk possible damage or tear it apart, possibly for no reason(others opinion). I have seen engines run for long time on 30w and engines with 10 psi at idle, but its a 340, not a pinto so I think it would at least be worth $20 to OP to determine issues or lack thereof without tearing it down.

OP if you do try 20w50, assuming you are not scared of others BS, please do not store oil in freezer or snow bank prior to pouring in engine. If its at room temp it will hurt nothing. I can offer some form of proof in that products like Power Punch or Lucas Oil treatment etc are VERY heavy viscosity and they wont "blow up" your engine when you put it in your oil. It will however, RAISE your oil pressure at least temporarily. Feel free to chime in anybody that has ever put this in an engine before....according to Rusty, viscosity has no affect on pressure, but then he also thinks Pluto is a planet and psi is "per square inch". Your engine, your choice. Remember, dont believe everything you read on internet, probably 80% is pure BS.