I've read through several discussions here about the competing views on the overall effectiveness of Top Tier gasoline. For the sake of this thread I am using a premise that Top Tier does have an actual detergency benefit (please don't fight that hypothetical here, unless you REALLY have to). But my question is whether there can be "too much" of a good thing? Specifically, there are several gasoline retailers advertising that their gasoline exceeds even Top Tier's requirements: Shell premium advertises as 7X the EPA standard; Costco advertises at 5X the EPA standard at all of its octane levels; Amoco and Exxon also both advertise that their premium gas has a higher level of additive than Top Tier requires. I see that these claims are made in relation to the EPA minimum, but clearly they are also exceeding the Top Tier requirement. So, again, the question is: does that "extra" additive actually provide a benefit that is useful/necessary in every tankful? Is there a point where extra additive is just overkill? Is it worth the premium that Shell charges or is it just advertising/hype? I would think that the upper limit would be an over-the-counter additive, and those are required/recommended only a couple/few times per year - not every fill-up.
Welcome personal/anecdotal insights, but any studies or lab comparisons you can provide would be GREATLY appreciated.
Welcome personal/anecdotal insights, but any studies or lab comparisons you can provide would be GREATLY appreciated.