Brian,
I believe you have it wrong. The bypass filter media doesn't or is not designed to restrict flow. The flow to the filter media is restricted by a very small orifice on the supply side of the housing. The one I saw, I think it was an Amsoil, the orifice was about 1/64" That is small. The idea is the filter media operates at a severely restricted volume. Since the inlet itself is restricted there is very little if any pressure drop across the filter media. As long as the inlet restriction is higher than the flow restriction provided by the filter media there will be no pressure drop and the oil will continue on its leisurely pace to be returned to engine nice and clean. Since the return hose simply dumps the oil back into the engine there is neligible pressure unless the hose was plugged! If the filter media itself was subjected to full volume/pressure there would be two problems at least. One would be the filter media would be forced apart or simply destroyed/eroded by the volume of flow. Imagine toilet paper subjected to a jetstream of hot oil..... And two there would likely be a loss of oil pressure and volume for the critical engine parts like bearings, etc. The small inlet orifice allows only a small volume of oil to flow through the filter media so it may be cleaned thoroughly.

Wasuchi,
How long have you had the Oilguard? What is the life of the filter element? What model filter are you using? What year is your truck? What lab do you use for oil analysis? Thanks, RT

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