An apparatus for heating a fluid such as engine oil includes an auxiliary pump, a conduit connected to the auxiliary pump and provides fluid communication from the auxiliary pump and an aperture in the conduit. In use the auxiliary pump contains the fluid. A first portion of the fluid is pumped into the conduit by the auxiliary pump and a second portion of the fluid remains in the auxiliary pump. The aperture restricts the flow of the first portion of the fluid in the conduit. The second portion of the fluid is heated due to friction between the second portion of the fluid and the pump. There is also described a method of heating a fluid.