Deposit-control additives have been required by the EPA in all gasoline since 1995; however, research shows that as much as 50 percent of the fuel on the market is formulated with less effective additives that employ the minimum additive legally required (known as the lowest additive concentration, or LAC), according to Scott Cushing, sales manager at ChevronTexaco. Although it conforms to EPA regulations, many believe that LAC gasoline provides inadequate valve cleanliness.
“LAC was actually created to help reduce exhaust emissions by keeping fuel injectors and intake valves and ports clean,” says Cushing. But the testing requirements were flawed such that even low doses of additives could pass the test, which results in excessive deposits that cause driveability upset. High fuel prices have forced consumers to shop around for the lowest cost, but when they purchase inexpensive gasoline, they may very well be buying LAC gas and unknowingly contributing to engine deposits, explains Cushing.
According to GM, Chevron recently became the first marketer to develop Top Tier detergent gasoline, a new class of gasoline with enhanced detergency. Using polyether amine additives, the fuel meets new voluntary deposit control standards developed last year by four automotive companies: GM, Honda, Toyota and BMW.
Based on the news report from GM, “Top Tier detergent gasoline will help keep engines cleaner than gasoline containing the ‘lowest additive concentration’ set by the EPA. Clean engines help provide optimal fuel economy and performance and reduced emissions. Also, use of Top Tier detergent gasoline will help reduce deposit-related concerns.”
Online reports say that many major fuel suppliers sell gasoline with a detergency additive called polybutene amine chemistry, or PBA, since it is less expensive and still meets LAC standards. PBA additives have a side effect. They can cause unwanted combustion chamber deposits, especially in the higher treatment levels needed to help clean injectors and intake valves.
PBA is also used in many bottled fuel additives, says Cushing. It can clean injectors and carburetors and also intake valves without causing harm, but only if it is properly formulated and used at a high dose. But, when used at these higher potency levels, he adds that research has proven it leads to combustion chamber deposits.
However, state-of-the-art additives based on polyether amine chemistry, or PEA, are considered “combustion chamber deposit neutral” — one reason Chevron is using it in their new Top Tier gasoline. PEA is effective in cleaning carburetors, fuel injectors, intake valves and combustion chambers and it will not cause harm to the engine, according to Cushing.
PEA chemistry can therefore be used at higher levels in gasoline and bottled additives required to maximize injector, intake valve and combustion chamber cleaning.
For jobbers, distributors and retailers selling bottled fuel additives, be sure suppliers are offering additives that use the appropriate chemistries and warn motorists regarding the different types of gasoline on the market, suggests Cushing.
Top Tier gasoline can be found at Chevron, QuickTrip, ConocoPhillips, Shell, MFA and Entec stations across the country. For more information, visit www.chevrontexaco.com.
