I can't speak for others, but FOR ME, being just DIY on my own vehicles, I use a mix of OEM and aftermarket parts. I'm careful about where I get any OEM parts, and the vast majority of aftermarket I get from Rock Auto. I always get AT LEAST stuff in the "standard replacement" category and never in their "economy" category. If possible, I usually get the part I know is the OEM supplier - Denso, Aisin, etc. I always research any brand I'm not familiar with before committing to purchase. FOR ME, the "value calculation" is vastly different from a pro. My income/livelihood doesn't depend on not having to redo a fix. FOR ME, my calculation is "the more of a PIA it is to redo it, the better brand part I will get." Some things I ALWAYS get OEM/OEM supplier, such as most electric/electronic items - plugs, sensors, etc. because there are too many variables, and it becomes a BIG PIA to troubleshoot to only find out an aftermarket sensor (for example) isn't responding the way it should, not giving the expected waveform, etc.
Got a set of NGK laser iridium from CT. Noting that they came with the cardboard sleeves. Production batch stamps of U399 and U2XM. At least for now, the engine idle shudder has gone away, no misfires through a test drive.
According to this vid, NGK will tell you if it's genuine. Note that there is the caveat in the vid about some fakes stamping production numbers from real batches.
Yeah if you know what to look for the counterfeiters do too what generally will get the counterfeiters Is the packaging like look at nipendensos real packaging That's expensive to recreate that and reprint that is not cheap so look at your packaging carefully the text the clarity of the letters the words themselves on the packaging misspelling commas in places where they don't need to be things like that is what get these Asian counterfeiters caught quickly
Spoke too soon. Misfire still. I'll test the resistance next chance I get to confirm that it's not just a bad spark. I swapped the order of the coils as well, 1,2,3,4 became 4,3,2,1. Misfire still only in cylinder#1 and only at idle or low start. Also bought a new used prius prime...