Well, a friend of mine a while back purchased a used (2000 model I believe) Nissan Frontier with the V6 engine. Has about 50,000 miles on the clock. He's had it for several months now, and just the other day, he told me that the engine threw three rods through the block. Well, he brought it back to the dealer (reputable place in town that sells both new and used vehicles). First thing they asked him for were his oil change receipts, but he said he didn't have any. ...Dealer said they found "sludge" in the engine (don't know exact amounts...this was all I was told). Now I don't know if he did change the oil or not, but could sludge cause three connecting rods to shoot themselves out of the block? Thanks.