Purchased a few Denso air filters. I've never noticed before but either the top or the bottom is textured whilst the opposite is smooth. I don't recall the OE filter having this. The one I bought from NAPA years ago is smooth on both sides.
Is there actually a polarity on the air filters for which is up versus down? Have I been this unobservant all these years?
Is there actually a polarity on the air filters for which is up versus down? Have I been this unobservant all these years?
