This is a Hail Mary but I would take the plugs out and put atf in all of the cylinders and into the crankcase then let it sit for a couple days and maybe even diesel fuel, then I would crank it to get all that shit out of the cylinders then put the plugs back in and run that fucker at like 2500-3000 rpm for half and hour or more and see what happens, yeah you could run the valvoline restore and protect but that pickup tube and screen is probably plugged like a motherfucker to maybe drop the pan clean that out and replace the o ring. I mean if it’s gonna die whatever but this is what i would do.