Wait, what? Can you summarize? I've always thought WIX was OK. I see mention of an issue in
@coax's thread but don't see an explanation of what in the filter failed. I have a WIX filter in the garage for the Tacoma that I got with a jug of oil. I normally use Toyota filters (Denso from Thailand) and don't plan to change but figured I'd use that WIX some day.
Yea there have been a bunch of folks on Mud who have experienced the issue. (Maybe a "bunch" isn't correct but enough to see a pattern with just that user group. Much to the surprise of folks when told to "try a new filter" and they get pressure back, unfortunately much too late and engine is roached
To summarize: the wix oil filters both an anti drain back and a bypass valve. The 80 series 1fz has two oil pressure relief valves in the oil circuit. one of them is immediately post oil pump which dumps right back into pan if pressure too high. The other one is further down the line in the circuit (on the PS side of the block as part of the oil cooler after the filter). If a failure in the oil filter does not allow for sufficient flow through the filter itself, there is no path to keep oiling the engine with unfiltered oil. Couple this issue with the fact most 1fz engine oil pressure senders and the subharness are so corroded most don't accurately reflect pressure. (I subesquently replaced both the sender and the sub harness when I rebuilt)
In essence it relies on the bypass within the filter. The suspicion is that something either doesn't allow for oil flow into the filter (stuck antidrainback valve) or that it doesn't allow oil out (stuck relief valve). Then the pump just circulates oil back into the pan.
In my instance there was an ever so slight amount of oil getting through the circuit but far less than there should have been.
Interestingly enough, there are a number of companies that do UOA on the oil to predict or confirm engine/component failure, but very few that acutally do mechanic failure analysis of components. I got the guys at blackstone to agree to do a one-off assessment of my filter even though thats not a typical service. They essentially found "nothing". I was pretty disapointed, just because I was generally curious to know what had happened. So...even though it is 100% clear to me that changing only one part of the system (the filter) clearly showed the filter was the issue, I still don't know what exactly in the filter went bad. I am also not aware of anyone else with a bad filter being able to ascertain what the failed component was. Personal guess is that bad rubber used in anti drain back valve and it got brittle/jammed/etc. I just don’t see a filter getting clogged enough in a 1fz , that is very easy on oil, during a standard oci, that 80psi wouldn’t push enough oil through the media if the pressure valve failed shut. That would be a super clogged filter.
On the plus side, both 15601-44011 and 90915-YZZD4 are cheap on partsouq ($8/$4) so I will now just stock up on those. My mistake was not having some on hand to use vs. the napa which was readily available when I needed to change the oil.
A few diagrams from 'mud.
Note the two double arrows "inside" the filter indicating the two paths (normal+bypass) within the filter. However, only one path into, and one path out of the filter. So any obstruction in the filter not allowing flow (filtered or unfiltered) will cause this issue and starve the whole engine.
Seems like toyota designed the system to account for not overpressurizing an oil filter but didn't account for having a filter that just didn't flow oil.