Working on replacing the spark plugs on a 2009 Volvo V70, 3.2L I6 (B6324S) engine. I currently have the new Bosch double iridium plugs (9615) torqued to ~15.5 ftlbs. Is there an optimal torque spec for this engine? Bosch says 28 nm, but I can’t find anything from Volvo in my manual.

 

I've seen 25 nm for other similar model Volvos. Not sure why the 2009 would be different. Key in my mind is to not overtighten so using a torque wrench is a good idea. The goal is to tighten enough to compress and seat the washer - anything in the 25-30 nm range should be fine.