Yeah, my 5-cylinder ranger doesn’t work so good...
I don’t know how handy you are, but 50 years ago on my first truck, a 3-wheel drive Chevy (it was 4-wheel drive 18 years before I bought it), I could drop the pan, shine up the crank with emery paper, put in a new bearing and get another 4-500 miles on it driving it gently. I was broke in college, and I could do the swap in about 1-1/2 hours in the snow. Did it three times before old “Candy” blew up. I paid $135 for the truck and sold it for $75 with the blown engine. Financially, it was probably my best automotive investment....
I agree with Ranger850, I don’t think there’s any oil that would make a difference without causing equal problems on the small ports. The viscosity isn’t the issue. Once there’s space (the knock), it will keep hammering out the bearing until it breaks.
If the engine is otherwise tight, before it breaks, if it’s not spreading shavings now, you could probably pull the crank without pulling the heads and pistons, and have it refinished or replaced for less money than a rebuild. I think the engine has to come out in a Ranger. My old Chevy, you could pull the pan and swap it if you just loosened up one motor mount...
good luck with it.