Champ Labs sent me this info:
2.5 psi pressure differential @ 3 gpm with 180°F SAE 30 oil. This does not tell us what gpm we get before the bypass valve begins to open, but evidently more than 3 gpm. The lowest bypass valve pressure I've seen is 8 psid, and the setting on your filter might be higher. I would not assume that the pressure rise through the filter media is linear with the flow rate. Note that this spec is for the small M1-102 filter which fits many Toyotas.
The filtration for this filter is 75% of 10 micron particles and 98.5% (absolute) of 20 micron particles.
Ken
[ January 26, 2003, 06:29 PM: Message edited by: Ken2 ]