Originally Posted By: BrocLuno
No, you are not harming that engine. It has a gazzilion miles and the clearances are big enough to swallow the 20W-50 just fine.
For the cold flow resistance, I'd install a bigger than stock (usually longer) filter. The increase in media area will reduce cold flow resistance.
Ford has been using that hex drive since forever. There are about a bazzilion Fords out there with hex drives intact. What usually takes them out is not oil pressure (the pump relief valve will open before that), it's debris like little bits of metal that get caught in the pump... That's why it is really important in Fords to use a magnetic drain plug...
If you keep the cold engine revs in mind and don't red-line it from the driveway, it'll last a l-o-n-g time.
There are a lot fire trucks here in the USA that are based on Ford chassis and engines and they have hex drive pumps. They do go from stone cold to red-line and they do not fail. Most are running fleet oils like Delo400LE (15W-40). But they survive just fine.
This "known problem" is a result of another minor engine failure shedding a piece of gear or chain or whatever, small enough to get past the oil pick-up screen and momentarily locking up the pump. Bingo - there goes the hex shaft
I had it happen to me on a 1963 Merc S-55 with a 390 4-speed (back in the day). But I was young and street racing and I over-wound the motor and there went the shaft. I fixed it and never had the issue again.
And for the oil-flow nuts out there - I drove that car three blocks with no oil pressure to where I could fix it. It ran fine. It clicked and clacked and ran. That was well before synthetic oils. Just good old blue Sta-Lube 10W-40
I agree
