What really is 'bad' gas?
By James R. Healey and Chris Woodyard
USA Today
Gasoline prices have climbed to near-record levels, sending more motorists shopping for lower-price fuel, and leaving many of them wondering if they are hurting their engines by burning the cheap stuff.
Their anxieties have lately been fueled by a $35 million Shell marketing campaign, warning that discount fuel is the petro-chemical equivalent of the road to hell.
There seems no easy answer to the simple question: What is bad gas?
Consider:
It's all about additives, which are engine-cleaning substances added in tiny amounts — a few parts per million — to ordinary bulk gasoline at fuel terminals. The type and strength of additives are the main differences among gasoline brands.
"We can prove there is a difference in fuels," argues Jens Mueller-Belau, Shell's technology manager for fuels development. "We estimate 50 percent of fuels are meeting only government minimum standards."
Shell, a Top Tier brand, bases its claims on a test by Southwest Research Institute. The laboratory ran an engine for 5,000 hours, using Shell fuel on half the cylinders, an unnamed fuel in the other half. The Shell cylinders didn't have deposits, and the others did, the lab report says.
Shell has several demonstration cars that work the same way. In 16 tests of 5,000 miles, each using a different brand of gasoline, the test cars' intake valves with the Shell brand had just one-eighth the residue as with other brands, according to data that Shell provided to USA Today.
Bunk, say some. "I see these ads on TV where Shell says, 'We filled up with Shell and some other gasoline and saw a difference,' and I think it's a myth," says engineer Thomas Darlington, a consultant formerly at the EPA.
"Gasolines today are very, very clean from the standpoint of not forming engine deposits" because of the EPA and industry requirements, he argues. What does he buy? "I'm not brand-conscious. I go for price, as long as it doesn't have ethanol." He says ethanol cuts mileage 1 percent to 2 percent, because it has a lower energy content than pure gasoline.
Regardless of which gasolines prevent it best, and whether it's a major or minor issue, the buildup of unwanted material inside an engine eventually could make the engine run poorly, use more fuel and pollute more. Such degradation usually occurs over thousands of miles and years of use. But it has happened faster, which is what triggered some automakers to institute the Top Tier standard.
Top Tier standards can require 2 1/2 to five times as much additive as the EPA requires, according to GM fuels engineer Andy Buczynsky. Even so, it adds less than a penny to the cost of a gallon, Buczynsky says.
Top Tier standards are endorsed by GM, Toyota, Honda, BMW, Volkswagen and Audi. Buczynsky says the automakers check fuel randomly for additive levels. Roughly 40 percent of the gasoline sold in the U.S. and 50 percent in Canada meets the standard, he estimates.
Some not on the Top Tier list say their customers don't care, and wouldn't pay the little extra. Tesoro, which retails gasoline through 800 of its stations and Wal-Mart, views the detergent issue as a gimmick. Tesoro doesn't put in additional additives because "our customers are price shoppers," says executive Lynn Westfall. "We don't get any complaints from our customers."
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