Originally Posted by Campbell

It is advertised by some brands that higher octane fuels have added detergents. Stating that they have "extra and/or special" detergents only available on their most expensive fuel. Maybe they do. I really don't know. They don't advertise when they are changing the blend during the change of the season. So I don't know what to believe from the petroleum giants.
I've also had some people tell me that using a bottle of STP injector cleaner works also. I've tried it and really haven't noticed any difference on cars that have 100,000+ miles on them. Still, every once in a while I throw a bottle in hoping maybe it is helping. Also, (I think I remember reading this) if you read the bottle it suggests adding it at every fill up. That adds approx. $5 a fill up. Not going to happen.
The only way I've ever seen a benefit and justification for an injector cleaning is with high flow competition injectors. This is when you send off all injectors, they get checked for operation and measured for flow. Then they are cleaned ultrasonically. Checked, remeasured and sent back with report. Kind of hardcore for a daily driven car.
As for clogged injectors, I tend to believe that unless:
1. The vehicle sits for extended periods of time,
2. You have a poor fuel filter,
3. You are running some crappy gas that likes to turn into varnish at the drop of a hat (Total speculation here),
you should not have any injector flow problems. Certainly not with a new 330 anyway.
If you feel the extra additives might help, for peace of mind go with the high octane. You bought a $40k car. Is 10-20c on the gallon going to hurt that much? Or maybe you can use a mid-grade and add an injector cleaner every month. Might be cheaper for you in the long run. There are probably bigger differences in additives between brands. Look-up and see who is the better for that. Just be aware that some brands come from the same big tank sitting at the port.
Personally, I think the decision should be based on octane alone. If we look at just this thread we see that an increasing number have had better results with a mid-grade. Low-grade has lacking performance and high grade a possible decrease in MPG however some increase in power via the butt-dyno. (I'd still like to meet someone that can feel a difference of 1-2 hp in a car. )
This is my own personal conclusion for the RX330:
Low-grade: some low rev hesitation, translation, lack of performance and lower MPG because the ECM might retard the timing to prevent knock. (I've never seen it but people here swear it happens to the 330)
Mid-grade: an all round good choice for the 330 as no timing retard, thus there is no knock. No reduction in performance and MPG that seem to excel the other grades.
High-grade: Decrease in power(very small) and lower MPG. However, a sense that you are feeling more power because you spent more money. And of course that wonderful thing called peace-of-mind. It is highly under-rated but should not be looked upon as a weakness or sign of stupidity. I love that feeling.
I still think 87 should be fine, but I'll never get to try it for multiple tanks as the wife insists on the premium

Originally Posted by Lexy GS430

Campbell, you have many good points, and my intentions for using premium is for long life of my engine that is if i plan to keep it that long, and i don't plan on racing in it just for comfort from work to home only.