The Denso's aftermarket oil filters are made in China and have a reddish anti drainback valve. They also come on some new Toyotas with a Toyota logo, still made in China.The N1 greenish hue adbv could be silicone, or high temp nitrile. I would vote for the latter. The email says silicone but it isn't from the maker, so it's a second hand source. They saying it's silicone doesn't mean it is. The factory knows what it is. I never had a Toyota adbv get hardened or show any kind of defect, so it really makes no difference. I suspect it is their special blend of nitrile. Nitrile is not a bad thing.What is the composition of the Toyota 90915-YZZN1 ADBV? Denso's website states they use 'silicon' ADBVs.
What is a "siliconized" rubber? I've formulated many silicone elastomers in a previous life (many black in color) and I've never heard of such a term.Most likely a “siliconized or nitrile rubber”. What % of silicone qualifies the ok to put on paper that it’s a silicone bypass?