hey guys. i have a 2017 gmc yukon xl with a 6.2 L with 80k on it. the wife drives it so miles are usually pretty gentle. had the oil changed recently and drove for 19 miles (40 psi on oil gauge) and no oil pressure warning lights all go off. i shut the engine down, checked the oil level (barely on dipstick) with smoke coming from the dipstick tube. let it sit, went and got oil and added 4-5 quarts just to see if it would make pressure- none-zero oil pressure. shut it down and towed it home. had the filter changed, changed the oil again (no metal) and still zero pressure. its also now making a small knocking noise where it was not before the loss of pressure. garage checked pressure with mech gauge, still zero. now they want to change the engine!! my question is, is this complete engine swap necessary or are they just being overly cautious? can i just change the oil pump? i know its a big process, but what are your thoughts of longevity of the engine? how difficult is this oil pump to change? i have seen a ton of videos and have the tools and experience working on engines, but dont want to spend $12k on a used motor swap!! please help!!!