Yes I'm back using the stock long reach copper plugs Denso K20HR-U11 and Caltex Havoline mineral oil with sludge cleaning agent. Been with it since 2009 and so far I'm sticking with these.

The only colder plugs for Innova was Denso IKH22 which is Iridium and it cost too much, and just the same if you encounter dirty (oily) LPG it will also gets fouling.

BTW, about a couple of months ago, I replaced my head cover gaskets (no. 1 and no.2) and I could see that my cams and internal parts are still metal clean...I'm now a believer of no sludge additives of Havoline

I'm tempted to try Mobil 100 LPG whenever I'm at ACE Hardware, but could not find the right time when to buy and carry 6 liters oil