gasoline quality

8/11/2019 Gasoline Quality

1/5

line Quality

//www.aa1car.com/library/bad_gas2.htm[1/31/2014 7:01:10 AM]

Home,Automotive Repair Library,Auto Parts,Accessories,Tools & Equipment, Manuals & Books, Car BLOG, Links, Index

.

Watch Out for Bad Gasoline

Copyright AA1Car (originally published 2006)

Adapted from an article written by Larry Carley that appeared in Underhood Service magazine

asoline qualityis an issue few people think about. When hurricane Katrina hit in the summer of 2005, gasoline prices soared.Everyone was scrambling to buy the cheapest gas they could find, and the sales volume of premium and mid-range gasolineropped. They said there was a serious fuel shortage, so refiners who were normally required to make reformulated gasoline (low

emissions) were temporarily allowed to cut some corners so they could produce more gallons of gasoline from each barrel of crudoil. Consequently, there was an unpublicized drop in both fuel quality and octane rating during this period. We also suspect that soil companies (but not all) also used this opportunity to cut back their use of detergents and deposit control additives in their gaso

When the crisis had passed, gasoline prices came back down, the panic passed, and the sales volume of premium and mid-rangeasolines went back up. Since then, gas prices have climbed back up to to over $3 a gallon -- but there is no hurricane to blame thme.

As far as we know, a couple of months of over-priced, sub-par gasoline during the so-called Katrina "crisis" did not cause manyoticeable problems with engine performance. Thanks to the knock sensor, most engines (even those with higher compression raan usually tolerate some deviation in the octane rating of the fuel -- at least for short periods of time.

But lately, it seems we've been hearing more complaints about driveability issues that are typically caused by a build-up of varnisheposits in the fuel injectors and throttle body, and carbon deposits on the intake valves and in combustion chambers. These

problems include engine knock after cold start or when the engine is working hard under load, hesitation problems when acceleraough idle, poor fuel economy and even misfiring (which often turns on the Malfunction Indicator Lamp).

We have not found any recent studies by the government or anybody else that addresses the issue of fuel quality or whether the lof detergent and deposit control additives in gasoline is sufficient to keep today's engines clean. But we suspect that if such a stuwere undertaken during the aftermath of hurricane Katrina, it would have revealed widespread problems with inadequate levels ofhese necessary additives in some gasolines.

ASOLINE DEPOSIT FORMATION

When deposit control additives are not adequate in gasoline, harmful deposits can build up inside the engine:

Fuel varnish deposits that form inside the injectors restrict fuel delivery and cause the engine to run lean. This may cause lean
http://www.aa1car.com/http://www.aa1car.com/library.htmhttp://www.aa1car.com/links_parts.htmhttp://www.aa1car.com/links_accessories.htmhttp://www.aa1car.com/links_accessories.htmhttp://www.aa1car.com/links_tools.htmhttp://www.aa1car.com/links_books.htmhttp://www.aa1car.com/blog/blog.htmhttp://www.aa1car.com/links.htmhttp://www.aa1car.com/index_alphabetical.htmhttp://www.aa1car.com/index_alphabetical.htmhttp://www.aa1car.com/links.htmhttp://www.aa1car.com/blog/blog.htmhttp://www.aa1car.com/links_books.htmhttp://www.aa1car.com/links_tools.htmhttp://www.aa1car.com/links_accessories.htmhttp://www.aa1car.com/links_parts.htmhttp://www.aa1car.com/library.htmhttp://www.aa1car.com/


2/5

line Quality


misfire, rough idle, hesitation, poor fuel economy and increased HC emissions. A lean fuel mixture also increases the risk ofetonation and preignition. These deposits tend to form during the heat soak period that occurs after the engine is shut off. Thehorter the trips and the more frequent the drive cycles, the faster these deposits buildup.

Deposits that form in the throttle body can reduce airflow through the idle bypass circuit affecting idle quality and smoothness.These deposits are formed by fuel vapors that rise up through the intake manifold.

Intake valve deposits from gasoline that does not contain enough detergent

Deposits that form on the intake valves can restrict airflow through the intake ports, causing a loss of high speed power. Theeposits can also act like a sponge and momentarily soak up fuel spray from the injectors. This disrupts the mixing of air and fuelausing a lean fuel condition, hesitation and reduced performance. Deposits can also cause valve sticking and valve burning. Intaalve deposits are formed by normal combustion byproducts, but may build up more rapidly if the valve guides or seals are worn a

he engine is sucking oil down the guides.

Deposits that form inside the combustion chamber and on top of the pistons increases the compression ratio of the engine and toctane requirements of the fuel. Too much compression can cause spark knock (detonation) if the fuel's octane rating isn't highenough. Over time, detonation can damage the head gasket, piston rings and rod bearings if it is not controlled. The knock sensoetect detonation and tell the PCM to retard spark timing. This will take care of the knock, but retarded timing also increases fuelonsumption and emissions.

A build up of carbon deposits inside the combustion chamber also increases the risk of hot spots forming that may cause engine-amaging preignition. The hot spot ignites the fuel before the spark plug fires, causing a sharp rise in combustion pressure. Under

extreme conditions (high rpm and load), preignition can burn a hole right through the top of a piston!

A condition known as Combustion Chamber Deposit Interference (CCDI) can also occur when the carbon deposits are so thick theposits on the piston and head make physical contact. This area, known as the Squish Area (piston to top of chamber), has alearance that is about as thick as a paper clip. This can cause a loud, metallic banging sound when a cold engine is first started. eposits are soft and will gradually flake off. But the flakes may lodge between the valves and seats causing a loss of compressio

misfiring and rough running when the engine is cold (a condition called Combustion Chamber Deposit Flaking or CCDF).

EEPING FUEL INJECTORS AND COMBUSTION CHAMBERS CLEAN

The formation of harmful deposits can be controlled by adding detergent-dispersants to gasoline, the most common of which ispolybutene succinimide. Used with a petroleum carrier oil, detergent-dispersants help keep the intake manifold and ports clean.These chemicals are more effective than the carburetor detergents that were once used in gasoline, but they must be used atoncentrations that are three to five times higher than the older carburetor detergents.

Deposit control additives such as polybutene amine (PBA) were introduced in 1970 to help keep injectors and intake valves cleanThe only drawback with PBA is that too much of it can increase combustion chamber deposits. Polyether amine (PEA), by

omparison, cleans fuel injectors and valves, and does not increase combustion chamber deposits. In fact, it helps removeaccumulated deposits inside the combustion chamber to reduce the risk of spark knock.

n 1995, the U.S. Environmental Protection Agency set minimum standards for additives in gasoline to prevent the formation ofeposits in fuel injectors. Gasoline refiners had to certify their additive packages met these standards, but some experts now say

original standards were set too low and do not provide adequate protection with some fuels and engines. The minimum EPA requevel is referred to as the "Lowest Additive Concentration" (LAC), and is typically found in the cheapest priced gasoline.

OP TIER GASOLINE

At the other end of the fuel quality spectrum are "Top Tier" gasolines. These fuels are recognized by the vehicle manufacturers asaving the most effective additives and in the highest concentrations. Gasoline retailers must meet the high Top Tier standards w

all their grades of gasoline (not just premium) to be designed as a Top Tier supplier. In addition, all the gasoline outlets carrying th


3/5

line Quality


brand of approved gasoline must also meet the same standards. Gasoline retailers who are currently on the Top Tier list includeChevron, Chevron-Canada (B.C. only), Texaco (Chevron supplied only), Conoco, Entec Stations, Esso, ExxonMobil, Kwik Trip/KwStar, MFA Oil Company, Phillips, QuikTrip, Road Ranger, Shell, The Somerset Refinery and 76. For a complete listing of gasolineetailers who are selling Top Tier gasoline, Click Here.

OLICING GASOLINE QUALITY

Unfortunately, fuel quality isn't something that is easily policed. Many states have programs in place to monitor fuel quality on eithan ongoing basis or "incident specific" basis. Most are run by the state's Department of Weights and Measures. Even so, the focumost of these programs is to make sure consumers aren't being cheated at the pump and get the full gallon they pay for. Someprograms also check fuels to make sure they do not contain too much alcohol. The specific density of gasoline can be field testedetermine its volatility and alcohol content. But testing octane and the amount and type of additives in the fuel requires expensive

aboratory testing. So this type of quality testing is rarely done.

According to one leading gasoline retailer (who sells a Tier One fuel, by the way), many gasoline marketers have reduced theoncentration of fuel additives in their fuel up to 50% in recent years!

Most gasoline refiners don't want to sell the public bad gas because they obviously want repeat customers. Even so, they also knohat deposit formation is a gradual thing that occurs over time. So if they cut back on the additive package to save a few cents perallon, nobody is the wiser -- and least not right away.

The problem occurs when people buy the cheapest LAC gas they can find every time they fill their tank. The low level of additivesow quality additives) in the fuel will not be adequate to keep their engine clean, and sooner or later they'll start to experienceriveability problems.

Worse yet, if a bad batch of fuel leaves a refinery and ends up in people's vehicles, it can cause even more serious problems. Theave been instances where too much residual sulfur in a bad batch of gasoline has caused a rash of fuel pump failures.

mmediate driveability problems may also occur if the fuel is contaminated with water, contains too much alcohol or the wrong typalcohol (methanol instead of ethanol). Alcohol is a great octane booster, but for ordinary gasoline the amount of ethanol should noexceed 10% (or 5% for methanol). The only exception here is E85fuel for "flex-fuel" vehicles that is 85% ethanol and 15% gasolin

E85 contains less energy per gallon than gasoline and runs leaner, so the vehicle must have a special fuel sensor so the PCM caompensate for the alcohol to maintain the proper air/fuel ratio.

ETTING RID OF FUEL DEPOSITS

When a vehicle is experiencing deposit-related driveability, performance or emissions problems, the deposits obviously have to goThe troublesome deposits can be removed a variety of ways. One cost-effective solution to deposit-related driveability issues is toimply add a can of fuel system cleaner to the fuel tank. The cleaner will slowly remove the deposits while the vehicle is driven. Th

only drawback with this approach is that it takes time -- maybe one or two tankfulls with the additive to make a noticeable differencThat may be too long for some people.

For those who want a more immediate fix, the cure usually consists of cleaning the throttle body with an aerosol cleaner, flushing njectors with a concentrated solvent or cleaning product, and/or feeding an intake system cleaner of some type into the engine w

is running to clean the intake ports, valves and combustion chamber.

f injectors fail to respond to on-car cleaning, they can be removed for more thorough off-car cleaning on special equipment -- oreplaced if they are clogged and can't be cleaned.

For heavy carbon deposits inside the combustion chamber, a top cleaner product may be added to the engine and allowed to soa5 to 20 minutes to loosen the deposits. An oil change afterwards is recommended because some of the cleaner will end up in the

crankcase.

For extremely stubborn intake valve and combustion chamber deposits, blasting the valves through the spark plug holes or intakeports with a soft media such as walnut shells is an easier fix than pulling and disassembling the cylinder head for hand cleaning.

To prevent the formation of new deposits once the engine has been cleaned, you should recommend using a top tier gasoline or
http://www.toptiergas.com/retailers.htmlhttp://www.aa1car.com/library/e85.htmhttp://www.aa1car.com/library/e85.htmhttp://www.toptiergas.com/retailers.html


4/5

line Quality


adding a bottle of fuel system cleaner periodically to the fuel tank (say every four or five fill-ups or when changing the oil every 300miles).

UEL CLEANING ADDITIVES NOT THE SAME

One very important point to keep in mind about aftermarket fuel system cleaners that are added to the gas tank is that they useifferent chemistries to achieve different results. As we said earlier, some chemicals such as PBA can clean injectors and valves b

may actually increase combustion chamber deposits. Other chemicals such as PEA can clean the entire fuel system as well as thombustion chambers.

For dirty fuel systems, you should use a product that is concentrated enough to provide some real cleaning action. But formaintenance, you only need a product that keeps deposits from forming.

One new fuel system cleaning product that has been recently introduced does something no other product does: it actually cleansand protects the contacts on fuel gauge sending units. The contacts on the sending unit are typically plated with silver-palladium tesist corrosion. But over time, residual sulfur in gasoline can corrode the contacts causing the gauge to rear erratically or not at a

Replacing the sending unit is an expensive job because you have to drop the fuel tank, so a more affordable alternative is to simpadd a bottle of this product to the tank and let it take care of the corrosion.

pdate: September 2012

hill ips 66 Survey Finds People Often Buy The Cheapest Gas

ccording to a recent consumer survey by Phillips 66, 80 percent of young drivers claim to be knowledgeable about proper car cabut their behavior at the fuel pump says otherwise. The survey, taken by 1,018 American men and women age 21-30 who drive aare primary purchasers of gasoline, reveals that nearly half (49 percent) regularly fuel up with unbranded gasoline, despite the fachat it is known to cause engine deposit build-up over time that can inhibit gas mileage and engine performance.

While 84 percent of respondents say they are more likely to care about their car's engine performance than its appearance, one in25 percent) millennial drivers admits they are NOT putting the best gas into their cars for long-term auto health. Their reason? Pr

They often buy the cheapest gas they can find regardless of its quality.

urvey findings prove that for more than half (54 percent) of those polled, cost is the most important factor when selecting which go use. In fact, 55 percent of respondents think the type of gas they use does matter for performance, but only 42 percent are likelake the brand at the pump into consideration before purchasing. And while nearly half of respondents (41 percent) think additives

ignify quality gas, only three percent think this feature is key when selecting their gas.

he survey says that although most drivers care about their cars, they often buy the lowest priced gasoline to save money in the serm, without considering the performance impacts the resulting engine build-up may be causing long-term.

OP TIER Detergent Gasolines, like Phillips66 and other brands, include MORE detergent additives than is legally required to impar performance almost immediately and minimize deposit formations in fuel injectors and the engine's intake valves.

ccording to the survey, 98 percent of millennial drivers who use inferior gas would upgrade, with 45 percent willing to switch ifuperior or branded gas increased gas mileage and 35 percent willing to make the change if they believed there was a difference he quality of the gas. The problem is, many think all gasoline brands are the same -- which is NOT true!

onsumers may think they are saving money by seeking out cheaper gas. But what they may not realize is that the discount gasolhey are buying actually can cost them money in the long run by compromising their fuel economy and causing deposit build-up inheir engine. By using a TOP TIER gasoline, motorists can keep their engines clean, maximize fuel economy and performance, adavoid the need for expensive fuel injector service down the road.

More Fuel Related Artic les:

Older article on Bad Gasoline (2003)
http://www.aa1car.com/library/fuel_gauge_diagnosis.htmhttp://www.aa1car.com/library/us10325.htmhttp://www.aa1car.com/library/us10325.htmhttp://www.aa1car.com/library/fuel_gauge_diagnosis.htm


5/5

line Quality

// 1 /lib /b d 2 ht [1/31/2014 7 01 10 AM]

Fuel Octane Ratings & RecommendationsTroubleshooting & Cleaning Fuel Injectors

About Alternative FuelsE85 Ethanol Alcohol Alternative Fuel

Troubleshooting Fuel Gauges

Click Here See More Carley Automotive Technical Articles

Related Links:

Top Tier GasolineChevron Gasoline Facts & Technical Information

Gasoline Quality Guide for Technicians (PDF file - requiresAdobe Acrobat Readerto view).

Need More Information On Gasoline or Fuel Quality? Try Google Search. Enter Keywords or a Phrase:

Be sure to visit our other websites:

AA1Car Diagnostic Help

Auto Repai r Yoursel f

CarleySoftware

OBD2HELP.com

Random-Misfire.com

Scan Tool Help

TROUBLE-CODES.com

Search
http://www.aa1car.com/library/octane.htmhttp://www.aa1car.com/library/2003/ic30336.htmhttp://www.aa1car.com/library/alternative_fuels.htmhttp://www.aa1car.com/library/e85.htmhttp://www.aa1car.com/library/fuel_gauge_diagnosis.htmhttp://www.aa1car.com/library.htmhttp://www.toptiergas.com/http://www.chevron.com/products/prodserv/fuels/bulletin/motorgas/http://www.aa1car.com/library/gasoline_quality_guide_2000.pdfhttp://www.adobe.com/products/acrobat/readstep2.htmlhttp://www.aa1car.com/http://www.autorepairyourself.com/http://www.carleysoftware.com/http://www.obd2help.com/http://www.random-misfire.com/http://www.scantoolhelp.com/http://www.trouble-codes.com/http://www.trouble-codes.com/http://www.scantoolhelp.com/http://www.random-misfire.com/http://www.obd2help.com/http://www.carleysoftware.com/http://www.autorepairyourself.com/http://www.aa1car.com/http://www.adobe.com/products/acrobat/readstep2.htmlhttp://www.aa1car.com/library/gasoline_quality_guide_2000.pdfhttp://www.chevron.com/products/prodserv/fuels/bulletin/motorgas/http://www.toptiergas.com/http://www.aa1car.com/library.htmhttp://www.aa1car.com/library.htmhttp://www.aa1car.com/library/fuel_gauge_diagnosis.htmhttp://www.aa1car.com/library/e85.htmhttp://www.aa1car.com/library/alternative_fuels.htmhttp://www.aa1car.com/library/2003/ic30336.htmhttp://www.aa1car.com/library/octane.htm

gasoline quality

Documents