Info on Filters. Oil, fuel, air.

[Barry Bordes]

Originally Posted by C. Ludwig

While I will agree that Fram has a poor reputation and I avoid them, your scenario is not accurate. The check valve only ensures that oil is held in the filter to avoid dry starts. The "dirt and particles" that might be entering the engine from the cooler come in through the bottom of the rear iron, up the iron to the middle of the filter, through the media, out of the filter, and down to the rear main. The only way for the bad stuff to get to critical parts of the engine is through the filter media (whether the engine is running or not). There is no possible way for it to "leak back into the motor".

I think you meant to say that the oil comes into the side ports of the filter and clean filtered oil is fed through the center.

Also any "dirty oil" from the inlet is also poised at the bypass valve (directly below it in the pan) ready to contaminate your cleaned oil if the bypass is opened during cold start-up. If you have a direct reading gauge you will see this happen at about 105-110 PSI (3rd Gen). During warm-up it is important to try to avoid this.

Barry