When using Shell Supreme, or another gas with Techron added, is there an advantage to adding additional Techron to your gas? Also if one is using Shell Regular is Techron as an additional additive necessary or beneficial? I use Shell Supreme 92 octane in my '95 Seville STS and Shell Regular in my wife's 2002 SLS. Both seem to run fine on these gasolines. I occasionally ad a bottle of Techron to each upon fill up, but wonder if I am wasting my money doing this?

For what it's worth, I rarely use Shell and NEVER use any additives and have never had any fuel related problems.

:rolleyes: For the flip side of the record, I'm a Shell user and a TECHRON booster. I have added no TECHRON to Shell gas in the 2 1/2 years that Shell has been designated as a Top Tier fuel. (Same as for Texaco and Chevron.) All 3 grades of a Top Tier certified fuel contain TECHRON in the same amounts, octane notwithstanding. Adding extra is a waste of money.

Why do I use Shell ?? Because I have a Shell/Citi Master Card which rebates me 5% of the cost of every gallon of Shell purchased. 5% of $2.50 is $.12, so that makes $2.38, and around here the Shell stations have 5 cents off sale every Thursday. So if I fuel the car and truck on Thursdays I get about $.17 a gallon off. No brainer.

Why do I use TECHRON with some gasolines ? Because annually I (or my customers) burn a stupendous amount of marine gasoline of different brands in various engines, both carbureted and fuel injected. I build marine engines for fun and profit and can see firsthand the cleaning effect of TECHRON in marine fuel systems and engine parts, particularly intake valves. You worry about your Northstar getting 25 mpg??? Some of these guys are ecstatic to get 0.5 mpg !!!