I have been wondering if there is any way one could know whether the bypass valve opened or not? You know, after oil/oil filter change, cut it open and inspect. The valve is supposed to open on cold starts too if required, so that only makes things uncertain as far as checking whether it opened or not.
Also, what do you think about oil filter magnets? Are they worth the price?
Another thing that I have to ask. After the oil filter reaches its interval, say 5000 km. The filter media is surely not re-usable but what about the bypass valves? Do they become useless after 5-10000 km? The reason I am asking this is, suppose some local dhaaba wala oil filter makers get the Japanese or Thai bypass valves from the old used filters and decide to use those valves in fake filters, will those valves work? (Not sure how easy it is to remove the valve from Japanese filter, on Thai as you saw it is basically a separate piece sitting on top of the filter)
As far as I have understood things till now, fake filters that may be sold as "Genuine" will not have the Jap/Thai like bypass valves/pressure plate used in them. Instead of a pressure plate, they use the spring on top to hold everything together and bypass valve is elcheapo like LEPPON filter, which is like a big knob in the filter hole or it is not there. SO it should be easy to differentiate between Fake & Genuine Toyota filter on basis of this i.e. shine a light in the filter hole and look for the type of bypass valve. Do you think this is a safe method to ascertain genuine Toyota oil filter?