Gas treatments
 

Every now and then I throw a gas treatment ( injector cleaner ) in my DD but I never thought about putting some in my Boxster. Is it a bad thing to put any gas treatments in these cars?

Treatment is a good thing, but use a good one such as Techron, and plan on changing your oil within one to two tanks of gas after the treated tank. The oil will collect some crud knocked loose by the treatment.

If the car isn`t driven everyday some FI cleaner is ok. Please no Seafoam in a Porsche.

What about Marvel Mystery Oil?

I have started adding some marine 2-stroke oil (TC W3). I first read about it in another fuel thread here on the forum and followed up with a few other reads. I am not taking any data or doing it religiously. I just have a bunch of oil to get rid of from not using my jet skis enough. If it is not all internet fiction, it seems like a great additive:
Been testing Oil
TC-W3 marine two stroke oil as a gasoline additive - G35Driver