Spin on can filter can have two internal valves. One is a bypass valve for the event where a the filter media clogs. This allows unfiltered oil to be circulated in this event. The bolt for the Honda filter housing performs this function.
Spin on may also have an anti drain back valve, the purpose of which is to hold oil in the oil galleys when the engine is stopped, rather than draining into the sump. This is particularly important for engines with hydraulic lifters, to avoid oil starvation during the next start up.
Both these valves can't be examined in the spin on filter with destroying its functionality. Something you wouldn't do before installation.
Those using spin on type must trust the manufacturer to make each and every unit they produce function as intended, and this includes valve design, valve assembly, and inspection before the can is sealed up.
Some valve designs are better than others. And reliability of the valves can be affected by careless workers when gluing in the valves.
If a bit of glue is dripped in the wrong place, or the valve positioned wrong during assembly, the bypass valve may be stuck open or hindered from full operation, resulting in unfiltered oil being distributed throughout is use. Engines can run fine with unfiltered oil, although wear factors increase in proportion to the oil's contamination level and particulate type.
If the drain back valve is faulty with errant glue or incorrect assembly, the valve can allow oil pressure to route backwards toward the return line to the filter. This effects drain back as well as lowering running oil pressure.
Classic car owners discovered their valve trains were noisy when certain filters were used. When the filter cans were opened, faulty internal valves were often found in certain designs. When a filter was used with properly functioning internal valves, the engine valve train noise was eliminated.
For spin on filters, you can't tell from the outside what the design or quality is on the inside. Brands are what you purchase, but the significance is only the paint and logo printed on the outside. Top name brands can have the cheapest internal parts and assembly costs.
Manufacturing costs are reduced by hiring unskilled labor, and omitting the quality control inspection. Cheap filters are not the same thing as inexpensive filters.
It's not about the filter media quality. It's about those internal valves.
For the above discoveries, I don't use spin-on filters on the SOHC4. I'm just not much of a gambler.
