That's why people shouldn't beat on their engines until the oil is close to full temperature. Also, when an oil filter goes into bypass the majority of the oil is still going through the media. Doesn't take a lot of bypassing to make the delta-p go below the bypass valve setting.Yes, exactly and a magnet will help filter the oil while the filter can not, heck, some winter areas and short trips oil may not ever warm it up enough at times. Unlike water temperature it takes a long time for oil to reach full operating temperature.