We recently had a meeting with the Fram filter people and had a chance to talk with their engineers about filters, and a couple of interesting facts came to light. First, most racers know about the Fram Racing filters, but what we didn’t know is that these larger filters are designed more around increasing oil flow through the filter. This tends to minimize a pressure drop in the filter, which also reduces heat. But the engineers also told us that to improve oil flow, these filters utilize a low-restriction paper filter material that isn’t nearly as fine as the normal street filters. Using a Fram HP-series filter might not be the best idea for a street engine that sees a lot of miles. The Fram engineers don’t recommend plugging the bypass valve that is often found in filter adapters on most engines because this can create excessively high oil pressures when the engine is cold since all the oil then must run through the filter. In the case of the newer Fram Tough Guard filter, these units also employ a trick screen over their internal bypass valves. This way, if the filter plugs (which should never happen to a car crafter), the screen will protect large chunks of debris from reentering the engine. If you care about your engine, it might be worth your time to spend an hour or two learning more about how oil filters work. It was enlightening for me.