Almost 2 decades ago, not long after manufacturers were forced to abandon carburetors in favor of fuel injectionand more highly engineered engines in the pursuit of federally mandated CAFE (corporate average fuel economy) and EPA standards, the automobile industry began to have pervasive problems with engine performance and drivability. Their customers were having significant issues with deposits collecting on fuel injector pintles, the back side of intake valves, and cylinder heads. Often the engines had to be torn apart to be cleaned and in some cases sandblasted (using soft media like walnut shells) to remove these deposits. Manufacturers pointed the finger at the oil companies, who pointed the finger right back at the automobile manufacturers.

BMW knowing it was the gas and seeking to reduce their liability, created a pass/fail test to determine if a particular brand was acceptable for use in their automobiles. If you used a non-approved gas, they would no longer cover repairs under warranty, which forced their owners to purchase only higher quality gas. This was a bold, but brilliant move on BMW's part and those standards were adopted by other manufacturers, and forced oil companies into compliance with the test. For the most part the issue was solved with the inclusion of a quality additive package. Chevron happened to manufacture one of the best additive packages available both then and now (Techroline/Techron), so most simply purchased a more generic version from Chevron for their fuel. Initially the detergent additives were most frequently found in the higher margin premium grades, but ultimately filtered down into lower octane gasolines. The Top Tier designation is simply the evolution of what was begun by BMW now joined by GM, Honda, and Toyota, in an effort to force the oil companies to continue to raise the bar. So yes, Virginia, there is a difference.

 

One of the greatest transformations in the history of the automobile, IMHO. The fuel injection systems of today are far superior to the carburetors they replaced in every way. Anyone who's ever tried to get a Quadrajet set up right knows what I'm talking about. In fact, any drivability problems I've ever had were on carbureted engines. Hard starting, stumbling when pulling out into traffic, flooding, are all things I experienced with carburetors but never with electronic fuel injection.

Dave

 

I agree, but you better believe fuel injection had some real growing pains. Fuel injection in the late 60's and 70's was a hit and miss proposition. I had a good one, a '72 BMW 2002tii which used a Kugelfischer mechanical injection pump originally developed for diesels. Very reliable, but complex for its time and required higher maintenance than todays systems. Other systems were far less reliable, and reputations for some manufacturers like Audi suffered as a result of their attempts to push the technology forward.

 

Agreed. Mechanical fuel injection is a whole 'nuther can of worms. It was the advent of 'cheap' sensors and microprocessors that brought EFI into the realm of practicality.

Dave

 

The nice thing about mechanical injectors though is no electricity is needed. So you can still drive with no battery or alternator.
And as a truck driver mechanical injectors are preffered over electric.

 

yeah, but you get better mileage out of electronic injectors..... or you could slow down 5MPH. (or put PR in your engine and gain 2 tenths)

 

I am kinda a fan of Shell too. I try to get Shell whenever possible and have noticed that I get more miles per tank. Where I live the prices are pretty competitive.

 

Ok, so I just got back from Oregon where they have 92 Octane versus the 91 I get in California... I got almost an entire mile more per gallon than I normally do... and I used Albertson's gas!

Why no 92 or 93 Octane in California!?!?!

 

Not the octane, probably one of the other variables... additive package in the fuel, ambient temperature, altitude, humidity, etc. Car and driver published a study several years ago and found that different octane ratings yielded the same MPG.

 

This may be true for a lower compression engine, but with something that requires a higher octane, using a lower will get you less MPG. With our trucks, the higher the better.