Thanks for that VX Kat...i did spot that thread while doing my intensive research on the Isuzu over the past few weeks...and it does seem uncertain to the reason for the engine 'Issues'.....

...i know from my JDM Subaru Sti and P1 (Prodrive) Subarus that the Japanese high performance engines were designed to run on 100 RON fuel (widely available in japan) and a lot of the Subaru STi fraternity over here in the UK got there cars re-mapped to run on the lower octane fuels over here (although it must be said that in recent years Shell V Power with a 99 RON rating is very popular with many high performance JDM owners using it religiously!!....I use it in my Forester STi)....

...Some of those that chose not to make allowances for the lower 95/97 ron that is the Regular fuel in the UK, did pay the price in the long term with catastrophic Engine failure! Usually in the form of big-end failure, with the shell bearings letting go!

Now, it appears to me that the JDM 3.2 V6 is designed to run on 99 Ron rated fuel...as above we have had the Shell V Power over here for some years (amongst a few other forecourts that now sell higher octane fuel)..

..So i shall certainly be running my VX on the best 99 Ron fuel i can get!

I would imagine the 3.5 was an engine specific for the US market, where lower grades of fuel are used....i wonder if Isuzu didn't quite get it right with the 3.5 and the result of 'Knock' eventually took it's toll on some of the engines????

Just a suggestion based on fuel related problems over here in the UK.