Premium Gasoline?

[Keebler Elf]

Was chatting with my barber and he swears by fueling up with premium gasoline once a month. The rest of the time he uses regular. He says he sees a noticeable difference (car runs better, greater mileage, etc.).

Is this bullshit or does the irregular use of premium gasoline make any kind of difference?

For clarity, we're not talking about performance cars.

 

[spraggamuffin]

Google BITOG etc and all websites will tell you it's a waste of time to use higher grades of fuel than recommended by the car's experts/manufacturers.

Fuel differs in terms of Octane but more so amounts of detergents added.

Different grades also differ in term sof the amount of ethanol added.

Shell premium for example may not only have more detergents added compared to lower tiered, but also has no ethanol, so better mileage may be had compared to 87 with more ethanol.

If your car uses regular, when gas prices drop, it may not be a bad idea to do a premium fill every now and then just for the higher detergent benefits alone.

 

[Gentlescorp]

Most American cars are ok with regular 85 and up gasoline, but almost all European cars needs better grade to perform better.

 

[AK-47]

I drive a Jeep and I notice a considerable difference in horsepower when I use premium

 

[james t kirk]

1. Unless your engine requires higher Octane due to a higher compression ratio, putting in premium fuel is a complete waste of money. Your barber is just fantasizing that he's getting better performance.

In a nutshell, the compression ratio is an indicator of performance and fuel economy. The higher the compression ratio, the higher the performance you will get. Unfortunately, when you use gasoline with a lower Octane rating, what happens is that the air fuel mixture ignites not with the spark plug, but with the compression in the cylinder. The result is engine knock, which is that loud (literally knocking) noise coming from your engine you hear when you hammer the gas peddle. Hearing knock is NOT GOOD. In fact, it's very bad. Not only are you not getting the proper performance out of you engine, you are beating the shit out of the piston and the bearings in your engine. Hence, most modern cars have knock sensors which tell the computer that engine knock is occurring and to retard the ignition timing in order to avoid the problem. The PROBLEM with retarding ignition timing is that you lose power. A lot of power.

So, all higher octane does is prevent engine knock. It does NOT magically add horsepower or toque. It's not a more potent form of gasoline. It deters engine knock so you get the power from your engine that the manufacture designed the engine to produce. That's it, that's all.

So if your owners manual says you should use 87 Octane fuel, you use 87 fuel. Putting 93 in your tank will accomplish absolutely NOTHING.

Now, if your owner's manual says use 91 Octane and you put 87 Octane in because you are a cheap cunt, then your engine will knock, the computer will retard the timing, now your engine won't knock, and you'll never know that the ignition timing has been retarded, but, you will be getting less power from your moto.

It is that simple.

The question to ask your barber is, "what does your owner's manual require in terms of fuel?" If it's 87, and he thinks that by using 91 once in a blue moon he's getting better performance, he's kidding himself. But hey, we all kid ourselves.

The real scam is the price for higher octane fuels. I doubt it costs 1 cent a litre more to produce high octane fuels.

 

[james t kirk]

I drive a Jeep and I notice a considerable difference in horsepower when I use premium

I have a bridge over the DVP I'd like to sell you.

 

[james t kirk]

Most American cars are ok with regular 85 and up gasoline, but almost all European cars needs better grade to perform better.

Depends only on the design of the engine. European engines tend to be smaller displacement (there is no replacement for displacement) and thus in order to perform, they will have higher compression ratios.

 

[james t kirk]

Sometimes as engine age and get a lot of miles on them, they might requires a step up in Octane (if originally an engine required 87, you may have to move to 89.)

This is because the tops of the pistons and the under side of the valve will carbon up. The carbon deposits can create havoc with some engines. But most people don't keep cars with 250,000 km on the motor.

 

[Ceiling Cat]

The best gasoline to use is the one the manufacturer recommends. Premium fuel does have more detergents and using it once a month will not hurt your car, but it will cost a little more. Using a fuel injection cleaner will also keep deposits off your valves and have the same effect as a high detergent gas.

 

[james t kirk]

Google

Different grades also differ in term sof the amount of ethanol added.

Shell premium for example may not only have more detergents added compared to lower tiered, but also has no ethanol, so better mileage may be had compared to 87 with more ethanol.

If your car uses regular, when gas prices drop, it may not be a bad idea to do a premium fill every now and then just for the higher detergent benefits alone.

Ethanol is fucking TERRIBLE stuff for a motor. TERRIBLE.

For this reason alone, and no other reason, it's worth buying your gasoline only from shell and the higher octane rating.

I remember when some of my fellow gear heads were first telling me about the evils of ethanol I just discounted what they were saying. Till it happened to me. Specifically my older toy car. It rotted out the rubber fuel lines, the fuel pump, gummed up the carbeurator with green moss. It was fucking terrible. (My old beast features a 327 high performance motor from the 60's and boy oh boy, did I learn what ethanol can do to an engine.)

Also, I know that Audi engines in the Q5 are terribly susceptible to damage from ethanol.

If you can avoid ethanol, avoid it.

 

[huckfinn]

If you can avoid ethanol, avoid it.

I would agree on older motors like yours (former gearhead).....but aren't newer motors designed to handle ethanol better?

 

[james t kirk]

I would agree on older motors like yours (former gearhead).....but aren't newer motors designed to handle ethanol better?

My L76 327 stock is 365 horsepower. It's about as simple of a motor as you'd ever find and yes, I only use Shell premium fuel in it now.

The line of thinking on ethanol is now that if you have a car that does not burn through a tank a week, you should try to avoid ethanol no mater what. A car where the gasoline sits is begging for problems due to the ethanol forming a green goo.

 

[Promo]

My L76 327 stock is 365 horsepower. It's about as simple of a motor as you'd ever find and yes, I only use Shell premium fuel in it now.

Was that a typo, did you mean L79 ?

Didn't Chevy put the L79 under-dog motor in Chevy II and stationwagons?

 

[AK-47]

I have a bridge over the DVP I'd like to sell you

I lend my car to my sister one time, when I got it back the car seemed sluggish to drive. So I checked the glove compartment for gas receipts, and sure enough she had filled it up with regular gasoline.

I always put in premium. I notice a difference

 

[james t kirk]

Was that a typo, did you mean L79 ?

Didn't Chevy put the L79 under-dog motor in Chevy II and stationwagons?

No, L76 is correct.

 

[Promo]

No, L76 is correct.

I think this is a typical GM nomenclature thing. In 64/65 I believe the 327 was called L-76, then L-79. https://en.wikipedia.org/wiki/Chevrolet_small-block_engine#327
In 2005-2009 there was an engine called the L76 https://en.wikipedia.org/wiki/LS_based_GM_small-block_engine

Same idea as the famed LT-1. The 70s it was the LT-1 and in the 90s/00s it was called the LT1

I had a 66 vette with a L-79. The RPO code was "L79" but the tag under the hood and show documentation said "L-79". I looked through a couple of Chevy engine books I have and they used both descriptors. Who knows which is right as GM themselves used both interchangeably.

 

[Promo]

I drive a Jeep and I notice a considerable difference in horsepower when I use premium

I have a bridge over the DVP I'd like to sell you.

I don't believe "considerable" is quite accurate, but depending on which Jeep engine AK-47 has what he says can absolutely be true.

You kind-of explained why yourself. Modern cars employ variable cam timing and ignition timing to optimize fuel economy and power and the computer uses several sensors in its mapping algorithm to do this. Specific to this discussion, if the car is using higher octane fuel, the computer will advance cam and ignition more, (potentially injector time) and use the knock, O2 and temperature sensor to determine when the safe limit is reached. Modern engines have 40+ sensors in use.

In AK-47's case, assuming his engine employees these technologies (most modern Jeep engines do for the last 20+ years), he should be able to see a small measurable improvement in gas mileage and/or acceleration/responsiveness with 91/94 octane vs 87 octane.

You mentioned the Audi Q5:
The standard 3.0L motor will see ~ 2mpg highway improvement and ~.1-.2 second 0-60
The supercharged 3.0L motor will see ~ 2mpg highway improvement and ~.2-.4 second 0-60 (the supercharged motor has premium recommended).
If you are willing to run >=93 octane in the supercharged 3.0L motor, you can have your ECM remapped to add 100HP to 450HP -- no modifications other than the code and even fuel mileage and driveability is improved. The unitronic version does not impact the car warranty.
https://www.goapr.com/products/ecu_upgrade_30tfsi_sq5.html

 

[AK-47]

In AK-47's case, assuming his engine employees these technologies (most modern Jeep engines do for the last 20+ years), he should be able to see a small measurable improvement in gas mileage and/or acceleration/responsiveness with 91/94 octane vs 87 octane

Yepper. Absolutely true.

I drive a 2012 Laredo X. It has a 6-cylinder engine with 290 HP.
Its got quite a bit more pep when I use premium

 

[whitewaterguy]

Would like to hear what nothemama has to say on this topic because clearly he's the definitive voice of all things automotive , and owls

On another not, my Harley calls for premium and I notice a significant difference In performance between non ethanol premium shell bs premium with ethanol. So it's shell only for my bike

 

[kid_kuh]

I've tried premium gas but hardly noticed the difference. I have noticed a huge difference when I put those octane booster on random fill-up. Could be the car.