# Top Tier Detergent Gasoline: Does It Improve Performance?



## SINC (Feb 16, 2001)

I recently came across this web site with some very interesting information on gasoline and its additives concerning engine performance and longevity by some of the world's best auto makers:

Top Tier Gasoline

On the site, they state in part:

"TOP TIER Detergent Gasoline is the premier standard for gasoline performance. Six of the world's top automakers, BMW, General Motors, Honda, Toyota, Volkswagen and Audi recognize that the current EPA minimum detergent requirements do not go far enough to ensure optimal engine performance.

The intention of the TOP TIER Detergent Gasoline standards is to create a winning situation for gasoline retailers, auto manufacturers and drivers. Currently, many gasoline retailers provide fuels with lower-quality additive packages that can build up deposits on fuel injectors and on intake valves. Others can build up deposits in combustion chambers and may lead to intake valve sticking. These lower levels of additives can have negative impacts on engine performance and vehicle responsiveness.”

The site covers the USA and Canada and recommends using these brands of gas here in Canada:

Chevron Canada 
Shell Canada 
Petro-Canada 
Sunoco Canada 

I normally use Husky fuel, but after visiting this site, I may switch to Shell or Petro-Can for my next long trip with the motor home to see if I notice any difference.

Anyone use a particular gas not mentioned here that they find improves performance?


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## CanadaRAM (Jul 24, 2005)

toptiergas.com

Administrative Contact: 
Domain Name Administrator 
General Motors Corporation 
300 Renaissance Center Mail Code 482-C23-B21 
Detroit MI 48265-3000 
US 
[email protected]


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## SINC (Feb 16, 2001)

So, GM owns the site, but what about the endorsement of the other five auto makers?

And why should that have any effect on gas quality or performance benefits?


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## winwintoo (Nov 9, 2004)

I don't know about it's "detergent" properties, but I have always used the highest octane (ie most expensive) Esso gas in my car and never had any trouble with the car and it still gets good milage (kilometerage?) after 14 years.

When one of the kids fills it, they usually put in lower octane (cheaper) gas or from a different dealer, and I can tell right away - starts knocking and less oomph.

Of course my car is little and I don't drive much, so the difference in price isn't going to put me in the poor house. 

Just saying.

Margaret


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## CanadaRAM (Jul 24, 2005)

> So, GM owns the site, but what about the endorsement of the other five auto makers?
> 
> And why should that have any effect on gas quality or performance benefits?


I didn't offer an opinion one way or another whether it affects the recommendations of the site. 

I just offer the data so people know where the information is coming from. It's too easy to assume that websites are produced by unbiased third parties. Knowing who they are gives the viewer additional context to judge the information on.


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## SINC (Feb 16, 2001)

CanadaRAM said:


> I didn't offer an opinion one way or another whether it affects the recommendations of the site.
> 
> I just offer the data so people know where the information is coming from. It's too easy to assume that websites are produced by unbiased third parties. Knowing who they are gives the viewer additional context to judge the information on.


Fair enough, that's a reasonable approach.


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## iJohnHenry (Mar 29, 2008)

Can't answer your last question SINC.

KIA has only seen Sunoco since I got her Nov. 06.

She jumps when I ask her. What more do I need??


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## eMacMan (Nov 27, 2006)

Additional octane above the engines needs will give zero performance boost. As for the detergents I would look for a gasoline additive or once a month find a long steep hill and climb it a couple of times with the engine wound up in a lower gear. That is the traditional approach to a carboned up engine and there is no reason it won't work now. 

Beyond that GM vehicles have always tended to carbon up because they have oversized engines and are geared for low revs on the highway. Result; decent highway mileage that drops drastically in the city and a tendency for the engine to suffer from carbon deposits.


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## MacDoc (Nov 3, 2001)

What he said....



> Wintoo wrote
> 
> I don't know about it's "detergent" properties, but I have always used the highest octane (ie most expensive) Esso gas in my car and never had any trouble with the car and it still gets good milage (kilometerage?) after 14 years.
> 
> ...


Well you are in an odd situation in that while the higher octane is a complete waste of money unless you have a vehicle requiring it ( detergent is another issue and has validity )..your - don't drive much has probably created a situation where you are carboned up like crazy so the higher octane is keeping pre-ignition at bay.

At 14 years - I'd not bother trying to correct it - cheaper just to keep buying the expensive juice.

Next car tho - save your gas $$ and use regular ( name brand - I like Shell ) and a decarboning additive once in a while to prevent the build up that occurs when cars are driven short distances and rarely warm up properly or get blown out by a high speed run.

••

Oh yeah a good synthetic oil after break in will help with short run driving.


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## EvanPitts (Mar 9, 2007)

People are under the impression that higher octane numbers are "better"...

A high octane number simply means the gasoline is harder to ignite. So in a car with a normal compression engine (of 7.5-8.5 to 1), regular grade fuel is entirely adequate. Most cars just need regular grade fuel, higher "grade" fuels are a waste of money.

High compression engines (9.5-11 to 1), on the other hand, will require higher octane fuel because regular grade fuel will preignite under compression. That is, the fuel will ignite long before TDC and sparking, which will cause "knocking", "dieseling" and possibly backfiring through the intake system. Higher octane fuel resists such ignition, being harder to burn, thus is a requirement for high performance engines, like the Chrysler Hemi, or other fairly wild sports cars. Your manual will clearly indicate whether or not you will need Premium fuel.

Then there is the case of supercharged or turbocharged cars. Generally, a forced induction engine will be of lower compression, but because of the higher cylinder pressures, one may need to use a "Mid Grade" fuel. Again, the owner's manual will specify the fuel needed. Of course, strap a rootes blower onto a car and one will have to go to the airport to get the seriously high octane fuels needed.

So "Premium" is not actually "better" - it is simply formulated for those vehicles that would otherwise have ignition or engine running problems.


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## MacGYVER (Apr 15, 2005)

EvanPitts is correct! Talk to any mechanic and they should tell you the same information as above.

If your vehicle says 87 then only put that in it. No need to go higher as it could cause long term damage instead and there is absolutely no benefit at all with going higher. If your vehicle requires higher then 87, then do not go lower then the required number of octane. Once again, due to what EvanPitts has said above.


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## ErnstNL (Apr 12, 2003)

I can notice a real performance difference when I use higher octane fuel. 
I know all the opinions, even Consumer Reports says it's a waste of money, most cars that stipulate high octane, like the Mini Cooper, can run perfectly well on regular.

Still, I notice a big difference when I have to pass a big rig on the TCH going up a hill. 

It does make a difference in my case and I've been driving for 34 years.


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## krs (Mar 18, 2005)

One can't really generalize about the octane requirement like all these posts seem to do.
It all depends on the engine.
For the Audi I drive, 87, 89 and 91 octane gas can all be used, the engine itself adjusts for the octane rating of the gas you put in - higher octane gives better performance and better gas milage.
Here is a blurb from a review that explains that a little bit:



> PERFORMANCE: The new 3.2-liter V6 is literally a chip off the old block of the 4.2-liter V8, as it is a modular development of that engine. Think of it as three-quarters of the V8, with a balance shaft to take care of vibrations caused by its 90-degree bank angle. It features Audi's new FSI system. FSI stands for ``Fuel Straight Injection,'' and, as it sounds, that means diesel-like direct fuel injection for the most precise control possible. Benefits include more power, a greater spread of power (helped by continuous inlet cam control), and reduced emissions and fuel consumption. FSI allows a higher compression ratio, contributing to efficiency. And it's high, at 12.5:1 compared to the more common 10:1 or so - but it can run just fine on 87-octane unleaded regular gasoline, although 91-octane premium is recommended for best performance. With 255 horses at 6500 rpm and 243 lb-ft of torque at 3250 rpm, power delivery is strong and very linear, and is aided by the very good six-speed automatic transmission. ``Tiptronic'' manual-shift mode is rarely absolutely necessary, but can add to the driver's enjoyment on the right kind of road.


2005 Audi A6 3.2 Quattro Review

Different brands of gas is another story.
Shell actually gives me noticably better gas mileage than Pioneer for instance - not sure why but it does.


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## MacDoc (Nov 3, 2001)

> can notice a real performance difference when I use higher octane fuel.
> I know all the opinions, even Consumer Reports says it's a waste of money, most cars that stipulate high octane, like the Mini Cooper, can run perfectly well on regular.
> 
> Still, I notice a big difference when I have to pass a big rig on the TCH going up a hill.


Then you either have a high compression engine or more likely a carbon build up problem.
I suppose it might be an injector problem too - perhaps high octane offsets poor vaporization by delaying ignition for a bit.

If you don't have a high compression engine and your car is relatively new I'd run an injector cleaner through and maybe a decarboning treatment.

If it's an older car....carry on - it's likely carbon.

•••

KRS - that is interesting tech and will be important as we move into flex fuel vehicles.


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## winwintoo (Nov 9, 2004)

Interesting, but remember, I drive my car and you guys don't   

It's 14 years old and other than oil changes, a new battery and new tires, I have spent $0 on repairs and it runs like a top as long as I use high octane gas. As soon as one of the kids fuels it using lower octane, we all notice a difference in performance.

I don't know or care what the compression rating is, all I know is that it's a 1994 Mitsubishi masquerading as a Dodge Colt. 

I'm not advocating this solution for everyone, but it works for me.

And, I thought Esso was a major brand - maybe I'm wrong.

Margaret


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## Reveeen (Aug 26, 2008)

ErnstNL said:


> I can notice a real performance difference when I use higher octane fuel. most cars that stipulate high octane, like the Mini Cooper, can run perfectly well on regular.


European, and Japanese cars that require premium fuel have a thing on the engine called a knock sensor. When the engine pings, the sensor "hears" it, sends a signal to the computer, and the timing is retarded (up to 10 degrees). Your gas mileage, along with any performance, immediately goes in the crapper. Under these conditions you save no money by buying regular gas.


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## monokitty (Jan 26, 2002)

SINC said:


> Anyone use a particular gas not mentioned here that they find improves performance?


I've used Petro-Canada, ESSO, Sunoco, Shell, and never noticed any significant difference worth noting in milage with my Mazda3 (and none of them at all make the car feel better performance wise, setting milage aside). I use ESSO primarily now, as I have points [Speedpass] with them. I've only seen a dip in milage when using no-name brand gas, and even then, not by much.


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## EvanPitts (Mar 9, 2007)

^^^
The Mini Cooper is a forced induction medium pressure engine, so you should probably use mid grade gasoline; but you should consult your manual. There is also a difference between gas sold here and gas sold in the States. Their mid-grade is like our regular. Some brands of fuel have up to 10% Ethanol in it, like Pioneer and others, so mileage may decrease a bit because of the lower heat content of the Ethanol - but with the benefit that you will never have a frozen fuel line in winter. (It will also scour the water out of the gas tank...)

The Mitsubishi / Dodge Colts employed a mildly brain damaged lean burn system that also afflicted late model rear drive Chryslers like the 5th Avenue, and as a rule, they actually run better on higher octane fuels. Same with old Oldsmobile 60 degree V-8's, which weren't high compression but would knock and diesel like all get out with regular fuels.

But for modern, fuel injected cars, unless they are high compression engines, regular grade is all the engine needs.


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## eMacMan (Nov 27, 2006)

EvanPitts said:


> ^^^
> Some brands of fuel have up to 10% Ethanol in it, like Pioneer and others, so mileage may decrease a bit because of the lower heat content of the Ethanol - but with the benefit that you will never have a frozen fuel line in winter. (It will also scour the water out of the gas tank...)


These were touted as oxygenating fuels which reduced the amount of CO in the tailpipe. True with old style carburetors. Modern engines are computer controlled and have almost zero CO emissions. I suspect computer controlled fuel injection would assume the engine is running lean and pump in slightly more fuel to compensate, thus the lower mileage. Generally 5-7% lower.


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## winwintoo (Nov 9, 2004)

EvanPitts said:


> The Mitsubishi / Dodge Colts employed a mildly brain damaged lean burn system that also afflicted late model rear drive Chryslers like the 5th Avenue, and as a rule, they actually run better on higher octane fuels. Same with old Oldsmobile 60 degree V-8's, which weren't high compression but would knock and diesel like all get out with regular fuels.


Thank you EvanPitts - I've had this discussion with a lot of people over the years that I've owned my car and all said that I was wasting money. 

I got the car brand new in the past 14 years, I've probably spent less on gas than most people spend on oil, but some people just can't resist giving me advice.

Margaret


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## eMacMan (Nov 27, 2006)

winwintoo said:


> Thank you EvanPitts - I've had this discussion with a lot of people over the years that I've owned my car and all said that I was wasting money.
> 
> I got the car brand new in the past 14 years, I've probably spent less on gas than most people spend on oil, but some people just can't resist giving me advice.
> 
> Margaret


If you don't drive very many miles and most of those are in town, then the engine is almost certainly carboned up. In this case high test gasoline will certainly go a long way towards preventing pre-ignition.


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## EvanPitts (Mar 9, 2007)

eMacMan said:


> These were touted as oxygenating fuels which reduced the amount of CO in the tailpipe. True with old style carburetors. Modern engines are computer controlled and have almost zero CO emissions. I suspect computer controlled fuel injection would assume the engine is running lean and pump in slightly more fuel to compensate, thus the lower mileage. Generally 5-7% lower.


It is not so much that ethanol makes the computer think the fuel-air mixture is lean, but that because of the reduced heat content in ethanol, drivers will tend to press the accelerator down further to gain the same feel and rate of acceleration. Plus, more accelerator will be needed when running at an even speed, because of the reduced power of ethanol.

However, all modern cars in the North American market are designed to accomodate up to 10% ethanol; and some vehicles (GMs) are now equipped with FlexFuel support (which can run on radical percentages of ethanol), and some other vehicles can be run with an alternate rate prom setup, like BMWs and VWs.

The one disadvantage of ethanol, next to slightly reduced mileage, is that it is hard on any rubberized gaskets in older vehicles. Newer vehicles usually use Viton seals, and have been using Viton for perhaps the last fifteen to twenty years. (Pretty much anything with high pressure fuel injection will use Viton for seals - thus, most cars made since the mid 80's.) Anything over about 20% ethanol will be very hard on old style seals, drying out the rubber or neoprene and making it crumbly.


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## EvanPitts (Mar 9, 2007)

winwintoo said:


> Thank you EvanPitts - I've had this discussion with a lot of people over the years that I've owned my car and all said that I was wasting money.


Well, it is wasting money, but if your car suffers from preignition or dieseling, then it is the only solution. Some people have good luck with mid grade gasoline, or even with mixing the grades by alternating. Our old Oldsmobile would knock like all craziness on regular grade fuel, so we ended up alternating high grade and mid grade. But we always did fill that car at the half, because the gauge didn't work properly and would get stuck at half, so you never knew how much gas was in the car.

Chrysler never did fix their lean burn system - which did work fine when in top condition but they quite often broke down rather quickly. Some of the problem was that they cooled the electronics by placing them into the air intake system, where they became pitted with any sand that was sucked into the air filter. Not to mention that they were very generous with the potting compound, so the electronics would get so hot it needed the airflow across it to help with cooling. (This is the main reason for failure - while every other manufacturer put the computer in the passenger compartment to keep it away from damage and the environment...)


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## Adrian. (Nov 28, 2007)

If it has a turbo you need premium. 

I used to be able to put half a tank of regular and half a tank of premium in my Audi RS4. The dealership said I had to at all cost put high test and maybe even half a bottle of octane boost. :lmao:


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## EvanPitts (Mar 9, 2007)

Premium is not always required on forced induction engines; but the Audi probably needs high test since it has a pretty high pressure boost, and it can wind itself up pretty quickly. One should always check the manual because many turbo setups are rather mild in boost, and are entirely at home with regular grades of fuels - but high pressure engines like the Audi (and higher performance VW engines in general) are a different beast altogether, especially if the timing is advanced further than would be the norm.


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## jeepguy (Apr 4, 2008)

My commuter car is a 2008 VW Rabbit, it says 87 to 91 on the sticker on the fuel door, the mechanic told me I should run premium at least every 3rd or fourth fill on it, i notice I get better milage when I run premium, I get 100km more per tank and is much zippier . My Jeep is a cheap girl and will run on anything she's not picky.


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## EvanPitts (Mar 9, 2007)

^^^
You should do what you are doing then. They sure make a variety of engines for the Golf / Rabbits, and I'm not just talking about Diesel vs. Gasoline, but one can order all kinds of variants, turbo or non-turbo, I-4 or narrow V-6. It's all a little confusing actually, but VW also has their own version of FlexFuel that they call the BiValent (which is not available in Canada, but standard in Brazil).

My Toyota is entirely happy on regular, and I was fortunate to not have filled up at the gas station the week that their underground tanks filled with water because of a broken cap.

My old Buick was picky like crazy, so I usually used mid-grade. When I was in the US I needed high-grade, and even then, the car didn't like it too much. But then again, the Rochester DuoJet that it had was a rather picky beast and was very hard to tune properly, and hated cool foggy days in the fall, when the carb turned into an ice cube. My old Buick could be quite cantankerous - but it was excellent for going on dates in because it was bigger than a Motel room.


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