Abstract: An engine protection valve to cut off flow of fuel to the engine when oil pressure drops below a predetermined level, comprising a piston 5 slidable in a bore 4 of a housing 2, the piston having a series of seals thereon which divide the bore into three chambers 20, 22, and 24. The chamber 20 has a fuel inlet 6 and a fuel outlet 7, and a valve seat 8 located between the fuel inlet and outlet. A restricted orifice 36 allows a restricted amount of fuel to pass from the chamber 20 to the chamber 22 thereby lubricating the bore 9 of chamber 22 and allowing the seal 16 to slide smoothly on the bore 9. The chamber 22 is kept at atmospheric pressure to enable the valve to operate and fuel to drain from the chamber 22 to the fuel tank through the conduit 40. An alternative arrangement is to lubricate the chamber 9 and seal 16 with engine oil from the chamber 24.