My 3.2 doesn't clatter or knock, so I doubt I'll try it.

And most often the source of noise in the SOHC 3.2L (mine is a DOHC) is clogged hydraulic lifters. I would think an oil treatment is more likely to fix that than something in the gas. FWIW Isuzu recommends running 0W30 Mobil One to quiet the lifters by flushing out the varnish. Some have reported success with this, others have not.

Steve Carlson - 95 Trooper LS expo rig
Serenity now!