Tegger, I don't want to get in a nasty debate with you, because I respect your opinion on many automotive matters. So please consider this challenge to your claim as being part of a friendly debate :-)
As smart as you are, in this instance I think you're mistaken :-) ExxonMobil gas is not Top-Tier. I don't know if it was Top Tier in the past (like 3 years ago), but it certainly isn't today.
"The Big 3" in the U.S. are ExxonMobil, ConocoPhillips, and Chevron. The first two are based in Texas, while Chevron is based in California (San Ramon, near San Francisco).
ConocoPhillips and Chevron both meet Top Tier standards to keep your engine and fuel injectors clean from nasty deposits that can affect the performance of your engine. However, ExxonMobil gasoline does /not/ meet the Top Tier standard that GM, Toyota, BMW, and Honda have supported.
ExxonMobil is cutting corners.
Here's an interesting article from a WardsAuto.com *automotive journalist* written less than a year ago--not a private poster to an Edmunds message board claiming almost 3 years ago he got a letter from ExxonMobil (which is what you're relying on Tegger :-)
Bill Visnic's article:
Top Tier Gasoline Still Low-Profile
By Bill Visnic WardsAuto.com, Dec 7, 2006
DETROIT ? The past year brought plenty of attention to the fuels industry ? attention for rising prices. Meanwhile, several oil refiners and auto makers would enjoy some extra attention for their ongoing effort to raise the quality of U.S. gasoline.
In early 2004, BMW AG, General Motors Corp., Honda Motor Co. Ltd. and Toyota Motor Corp. announced they had agreed to a standard for gasoline that would guarantee a certain amount of detergent additives to help prevent deposits that tend to foul fuel injectors and stick in other tight-tolerance areas.
Top Tier gasoline logo developed by Chevron.
The group of four auto makers proposed gasoline with detergent additives that exceeded the Environmental Protection Agency?s minimums ? which they are convinced are too low ? ?Top Tier,? and recommended Top Tier detergent levels for all grades of unleaded gasoline.
Although several big-name oil refiners and retailers eagerly joined in ? including ConocoPhillips, Chevron Corp. and the Shell Group ? the ?profile? of the effort has remained low. As has Top Tier?s market penetration.
?About 40% of gasoline in the U.S. market now meets Top Tier requirements,? says Keith Corkwell, regional business manager of gasoline additives ? The Lubrizol Corp., one of the nation?s largest suppliers of gasoline detergent additive, which is the most prevalent type of gasoline additive, although there are many.
But the auto makers and oil retailers were hoping for a markedly larger market penetration by now, more than two years after Top Tier was first adopted.
A smooth marketing rollout of Top Tier ?didn?t happen,? says Jim Spearot, director-Chemical and Environmental Sciences Laboratory, GM Research and Development.
OEM Group Pushes for New Gasoline Grade
?We?re making progress,? Spearot says, adding, however, ?In terms of providing information to the customer, we?ve got some work to do.? Spearot agrees with Lubrizol?s Corkwell regarding Top Tier?s market penetration, although he reckons the figure may be closer to 35% of U.S. gasoline sales being Top Tier.
For consumers hypersensitive about the cost of gasoline, Corkwell says assuring a proper amount of detergent additive to guarantee the Top Tier standard costs ?fractions of a penny per gallon of gasoline.? Moreover, he reminds that one of the requirements of the Top Tier standard is that gasoline retailers provide it for all the gasoline they sell, not just higher-cost premium grades.
Corkwell says it benefits gasoline retailers to try to differentiate their fuels, and that Top Tier is an excellent vehicle for branding and image. ?Oil companies themselves have done it in the past,? he says, some promoting their gasolines? detergent qualities before the advent of Top Tier.
Spearot says GM is recommending Top Tier gasoline in every vehicle owner?s manual for the ?07 model year, the first time GM has promoted Top Tier in such a way.
He says contemporary engine-management systems provide ?calibration to such a fine line,? that deposits fouling fuel injectors or combustion chambers can markedly affect engine operations.
?We did this (advocated Top Tier) as a mechanism to help solve performance problems,? says Spearot.
Spearot says after the EPA first designated a minimum standard for detergent additives, there was ?slippage? in the concentrations that meant some gasoline suppliers did not have adequate detergent levels. ?I do believe the detergent levels have been improved,? he adds.
While work goes on to increase the market penetration of Top Tier gasoline, Corkwell says Lubrizol also has turned its attention to E-85 / E85, the widely promoted alternative to gasoline that is a mixture of 85% ethanol and 15% gasoline.
He says Lubrizol currently has research programs under way to determine what sort of additives might improve E85?s chemical composition; high levels of alcohol are known to be corrosive to many engine and fuel-system components. ?The need for additives in E85 is a question open for interpretation,? Corkwell says.