Reducing ZDDP by half in a single step would be a significant contributor towards whathas been called a revolutionary change in engine oil technology. Stepping it down from 0.10 percent to 0.05 percent over two engine oil category upgrades and several years, as may be done, might fall into the evolutionary range. Either way, industry faces a considerable challenge in applying oil with lower ZDDP to older vehicles.

There may be another approach to reducing the damaging effect of phosphorus on catalysts: scavenge it. That is, reduce the amount of phosphorus available to reach the catalytic converter, through the use of an organic manganese compound called MMT (a trademarked shorthand for the full chemical name, methylcyclopentadienyl manganese tricarbonyl).

MMT is a gasoline additive, primarily an octane booster for unleaded gasoline. It was introduced by Ethyl Corp. of Richmond, Va., in the late 1950s and is heavily used in over 20 countries worldwide – including Canada where it is currently found in 80 percent of gasoline. It sees more limited use in the United States.

In addition to its primary role in boosting octane, Ethyl claims that MMT scavenges phosphorus during combustion and allows it to be converted into stable, non-catalyst-poisoning form, reducing the actual amount of phosphorus reaching the catalyst by 60 to 70 percent.

Multiple Benefits
MMT is the most proven fuel component in history, Ethylclaims. According to the EPA, says Ethyl, MMT will not cause or contribute to a failure of any emission control device or system. The improvement in emission system durability [from MMT use] is long-term and occurs regardless of vehicle model or emission system configuration.

In 1995, when EPA granted Ethyl a waiver allowing the use of MMT in conventional gasoline, it found that MMT effects on carbon monoxide show a small decrease. For oxides of nitrogen, a more substantial and more consistent decrease was seen, leading EPA to conclude there was no increase in hydrocarbon emissions, says Ethyl.

EPA determined that U.S. refineries alone could save up to 30 million barrels of crude oil a year by utilizing MMT, resulting in less carbon dioxide [emissions], because less energy is expended to refine higher-octane gasoline components, Ethyl also states.

Automakers suggested that MMT was harmful to on-board diagnostic systems, but in 1998, Ethyl said, the government of Canada weighed in: Current scientific information fails to demonstrate that MMT impairs the proper functioning of automotive on-board diagnostic systems, it said, adding, MMT poses no health risk.

California Dreaming
Last month California drastically tightened carbon dioxide limits to become effective in 2009, to reduce the effects of greenhouse gases. Ethyl noted, In a vehicle using MMT fuel, less greenhouse-gas-forming nitrous oxide is emitted because the catalyst maintains a higher nitrous oxide-reducing catalytic action. It is estimated that over the lifetime of that vehicle this would be equivalent to a 3 percent reduction in greenhouse gases, as nitrogen dioxide is estimated to have 310 times the greenhouse gas-forming capability as carbon dioxide. Reductions in greenhouse gases associated with the use of MMT would be equivalent to the removal of many millions of vehicles from U.S. roadways.

So, in addition to dramatically reducing phosphorus in engine oil and its poisoning effect on catalysts, MMT claims a multitude of other environmental benefits. It would seem a win-win situation.

Not so fast. Jo Cooper, president and CEO of the Alliance for Automobile Manufacturers, strongly disagrees. It is our hope that EPA will recognize the impact of this [MMT] additive and take the appropriate steps to ensure its removal from our fuels, Cooper bluntly urged last week.

The impact Cooper was speaking about was the findings of an $8 million study of MMT conducted by the AAM, the Association of International Automobile Manufacturers and the Canadian Vehicle Manufacturers Association. The study began in 1996 and the results were released on July 30. A 56-vehicle test fleet supplied by six manufacturers was driven 3.65 million miles during the six-year evaluation. The three auto groups declared, The data produced by the tests represent the most comprehensive information currently available about the emissions effects of MMT.

Among the key findings, they said, was that MMT impaired catalyst and emission control performance and caused low emission vehiclesto fail hydrocarbon emissions standards.

The study also showed that, compared to low-emission vehicles driven on clear gasoline, at 100,000 miles MMT fueled low-emission vehicles had:
31 percent higher hydrocarbon emissions;
24 percent higher nitrogen oxide ofemissions;
14 percent higher carbon monoxide emissions;
2 percent higher emissions of carbon dioxide; and
2 percent lower on-road fuel economy.

An evaluation of MMT’s effect on on-board diagnostic systemswas not conducted, nor did the study evaluate MMT’s impact on phosphorus in gasoline engine oil.

Ethyl’s Response
Ethyl received a copy of the report when it was made public last Tuesday and is evaluating it. Meanwhile, Rich Mendel, Ethyl’s vice president for worldwide MMT marketing, commented, The auto industry has spent six years and over $8 million on a secret test trying to find a problem they could not, and cannot find in the real world. Over the last 25 years, tens of millions of vehicles fitted with advanced emission and engine control systems have traveled trillions of miles using fuel formulated with MMT without any problems.

When asked about the automobile industry’s motivation, Mendel stated, Auto companies strive hard to reduce their costs across the board. One way to reduce costs is to reduce variability in fuels so that testing costs for EPA certification can be lowered. MMT is a variable in the fuel so, even though it can dramatically improve the durability of a catalyst as well as reduce controlled atmospheric pollutants, auto companies feel that the extra certification costs offset that advantage. That’s it in a few words.

The cost factor has long been cited by General Motors. In April 1987, GM Canada stated, With regard to the use of MMT-free fuel in emissions testing, this becomes an issue of economic practicality. GM alone conducts literally hundreds of emissions and fuel economy tests each year in the validation of the new fleet. To repeat all of these tests on a second fleet of cars would be very costly.

Where to now? AAM’s Jo Cooper has made a straightforward request to EPA – ban MMT in fuels – based on results of a large laboratory and field study. Ethyls Rich Mendel states that trillions of miles of real world usage have not revealed any MMT problems. Grounds for compromise? Stay tuned.