I own a 02 dodge ram with the 4.7 magnum engine.I was on my way to work one day and all of a sudden started heaering a knock pulled over when noticed the oil pressure go all the way down and truck shut off on its own..put oil and turned it on and step on gas the truck would barley move felt power less...ended up getting a tow truck to bring it home...its been parked for about 2-3 months i turn it on once in a while and has power only thing wrong is the knocking sound i got a mechanic to check it out said he would charge me 1200 to tear up the engine and do some work to it...Is it worth it i thnk its proly oil sludge thats making it run poorly and maybe messed up something inside their due to the lack of sludge he said he can have it repaired within 4 days i just want to know if it would be better to get a used engine with 75000 or have mine cleaned out and fixed.