I've always thought very highly of Red Line's SI-1 Fuel System Cleaner; I've been putting a bottle of it into my Sube's gas tank every once in a while.

I've noticed that when I do, my Subie's gas mileage increases by about 2 mpg, as well as show a bit more power and even smoother running ....which is not to say that my Sube hasn't been running smoothly, it has....but then I always use mid range gas (89 octane) instead of regular (87 octane).

With the SI-1 added to the gas, accelerating from lower rpms in 3rd gear, for example, is smooth as silk without a hint of roughness or lugging.

I'm guessing that the SI-1 increases the efficiency and combustion of the gasoline; the formulae of todays gas, I'm sure, leaves a lot to be desired.

Of course, aside from performance improvements, it really cleans out the fuel system and combustion chamber.

But what factors or compounds in SI-1 would actually account for it's ability to increase gas mileage and improve overall engine running?

Various injector/fuel system cleaners use different formulations, but in general they have a base of something like kerosene or Stoddard solvent (mineral spirits), with naptha, benzene, amines and/or some proprietary ingredient(s). Depending on what's ailing a particular engine, one formulation may work better than another. Following are links to Material Safety Data Sheets (MSDS) for some of the brands, which will provide an idea of what they contain.

 

Red Line SI-1:

http://www.redlineoil.com/msds/49.pdf

 

Techron Concentrate:

http://www.jeadauto.com/msds/chevron/techron-concentrate.pdf

 

Shell V-Power Fuel System Cleaner:

http://msds.walmartstores.com/cache/49135_1.pdf

 

STP Complete Fuel System Cleaner:

http://www.thecloroxcompany.com/products/msds/armorallstp/stpcompletefuelsystemcleaner4-03.pdf