You certainly have more knowledge about this than I do. Sometimes I just like to argue for the heck of it. It is in the best interest of this board for me to concede my arguement.

I must say that my wifes Volvo only revs at 4000 when I drive , which is not very often. Almost all her trips are less than 3 miles and many more are less than 1 mile. My wife works 2.5 miles from our house and the food store , dunkin donuts, the hairdresser and her friend's house are all less than one mile. I change the oil every three months regardless of mileage. I must be lucky that we have not experienced the problem. Actaully our Volvo is almost trouble free, it even has the original battery.

I have two friends that own autobodies and they shuffle cars constantly. They always run into gas fouled plugs. They even have a machine to clean the plugs.

The question I would have: is this problem unique to Volvos or do other brands with four valves per cylinder have the same problems. It could have something to do with the combustion chamber design.