Didn't know you worked in a shop. I must have had a few "difficult" customers that day or something.... you know like the ones that keep bringing something in to fix and it's broken because of something they are doing but refuse to do different.
Like killing bar oil pumps in a saw... because they are dumping in whatever **** slurry of goo handy... stuff that might have been usable engine or gear oil 10 years ago.... so... my apologies.
Toe setting all depends on the tire size and suspension setup, though I can't think of many pickups that called for 0* toe. It's been almost 15 years since I've worked in a shop that had an alignment machine though.
For a long time I sent in oil samples on several vehicles I owned and even at 20-25k miles the same oil it was coming back ok. That with with using Shaeffer or Rotella 5W40. At $23/gal for Rotella it's not something I'd like to use for starting fires in the shop stove early. I usually go 10,000 miles, depending on what the oil is in. For equipment, 250-300hrs.
My C30 dumper I'm not sure I'll ever bother to change the oil, maybe just the filter every year or so. It uses and leaks enough oil to keep it topped off with fresh oil. I think I went through 2 gallons in it this year, maybe did 10,000 miles.... granted working the old 160hp small block pretty hard.
1/4 inch toe in? I dont use a measuring tape. I use a john bean wireless aligner at work. and and 0 toe is within GM spec. I actually have it set toe in on 0 degrees...yes the alignment machine is that precise. Like you said i realize driving the wheels do slightly toe out.
I do oil changes that often cause i get oil at cost. oh and i use a 15 $ k&n filter too.
I see far to many cars on 15000km oil change intervals and the filters are half collapsed. Oil and filters are cheap imo.
And worn out/loose ball joints and wheel bearings....change/affect your alignment. So a bad "alignment" will attribute to cupping
Not disagreeing as shocks will cause cupping as well forsure.