Small metal glitter in oil.

I hate to think someone could be that terrible of a person...but you very well may be correct here.

 

Also if you don't clean a drain pan that's had glitter in it before extremely well, you'll see glitter in changes for years, the little shavings hold onto the plastic pans like nothing else. When in doubt drain your oil through a coffee filter and check that.

 

What slimy scum

 

Smells like a ploy to get you to buy a new truck with a low-ball trade-in for your "damaged" truck. You know the dealer better than anyone here, but I'd be looking for a different place for service.