Servicing Your HMV Oil Filter

Back in the days of acetylene headlights, most vehicles were not equipped with filters to protect their engines from dusty air or dirty oil. This was mostly because it was simply not known how much damage dust and grit could do inside an engine such as scoring cylinder walls, scuffing piston rings, and scouring bearings and other moving parts. Of course, the tolerances in the engines of this period were loose and sloppy. They were low-compression, low-RPM, and not very long-lived.

All engines could have been fitted with air cleaners if their manufacturers had realized the need. No matter how old or primitive an internal-combustion engine might be, the air needed for combustion of fuel is sucked into its intake manifold by vacuum created when the pistons go down on their intake strokes. Therefore, an engine’s air may be cleaned of dust and grit by pulling it through a fine screen or filter before it goes down the carburetor throat.

Oil filters, on the other hand, would still have had to wait for a couple of decades.

Why? Because most early engines did not have oil pumps. Instead, they were lubricated by a splash system. There was nothing except the action of the crankshaft and connecting rods to splash oil onto pistons and cylinder walls. The crankshaft bearings were lubricated by dipping into the oil pan with every rotation. It’s difficult to filter oil that’s simply being splashed around.

With a splash lubrication system, about the only way to filter the oil is to put a screen in the filler pipe so the oil gets filtered when you first pour it in. Indeed, many engines had such a screen... which may attest to the quality of motor oil during those times. Even up into the 1970s, many gas stations still sold “bulk oil” of a nasty gray-green color from glass quart jars with open funnel-like tops, and these open jars sat outside in racks no matter what the weather.

Still, if oil is of good quality. as well as changed often (Ford specified 500