Originally Posted by ZeeOSix
Yep, you mean like the "hockey stick" shaped efficiency curve Purolator described to me in an email which I mentioned in that thread - see the graph below, which is also from Purolator.
When the efficiency increases towards the end is when the filter is nearly completely clogged and the delta-p is increasing quickly.
IMO, that's not exacrly where I'd want to run my filter to make it more efficient right before the bypass valve is ready to open and stay open. ...¬
Couldn't agree more with you. I guess my point is that it technically occurs, a spike in efficiency - just before "failure".(don't think that's the best word for it but meh)....but it's one of those, just because you can doesn't mean you should situations - running the filter right up to the end of it's performance life. Like I mentioned I don't do extended drains for a number of reasons, so it's not something I lose sleep over.
Here's a question Zee.. how much of a concern is "particle population" for sub 20 micron particulates on engines doing extended drain intervals??? If a filter has a less than 50% efficiency at the critical 5~10 micron range, won't the oil be slowly accumulating (net gain) particles in that range, over the extended drain interval? Seems to me that despite the marketing of extended drain oils by the oil companies, not all vehicles are a good candidate for this. If say your car has a problem with blow by and particulates entering the system (ingress), should you be doing extended drain intervals at all???
I would think these are vehicles that should stick to 4~7.5k intervals to avoid growing the very damaging 5~10 micron particle population.
Originally Posted by seekingbuddha
I am not losing sleep over these details, cause this should not be a concern for an average car owner - perhaps those in racing might care. There is plenty of other aspects in a car that could go wrong, before these issues play a role on engine.
Ditto and agreed 👠for the most part. It could become an issue over the long term in re engine wear. Those 5~10 micron particle size accounts for something like 70% of engine wear at critical points (boundary lubrication, tight clearance) like the main bearings, rods, cam lobes, bearing journals, valve guides, piston/cylinder walls etc..