1995 GMC Sierra, Bucket Truck, 55,656 miles Story: 35 MPH #1 piston came apart and the connecting rod (which was still going up & down) beat the big pieces into little pieces; this smashing process bent the connecting rod until it punched a hole in the cylinder wall at which point the wrist pin lodged in the hole and stopped all movement. Purchased a Re manufactured engine (Mexico) with a flat tappet camshaft that needs to be broken-in properly, which leads to my question: When this engine starts for the very first time, would a new oxygen sensor be damaged by the burning of oil in the cylinders; I'm thinking of leaving the old sensor in until after camshaft break-in ? ? ? My History, I was born in 1946 and stopped working for an employer in 2010. I served aboard the USS INTREPID CVA11 in the 1960s. The Intrepid is now a museum in NYC. As a former crew-member I did volunteer duty on board 2009 & 2010. Last Year I volunteered at a water powered mill in Wilmington, DE. In 1993 I replaced a (4.3L) 267 cu.in. SB with a (5.7L) 350 cu.in. SB in a 1979 Chevrolet Malibu wagon (everyone called it a sleeper). That was the extent of my engine swapping until now. My SON just bought an electrical business from his employer who was getting out of the trade; the bucket truck was part of the deal. Less than a year later the engine seized and he wasn't getting the work he was hoping for (no money for the bucket truck). Enter volunteer DAD with the money for the engine and the tools to do the work. Thanks for any advice !