Fact or Fiction?: Premium Gasoline Delivers Premium Benefits to Your Car

[1994Saturn]

I put 93OCT In my DYT4000 18.5HP B&S Engine. (Also It has 5W30 SYN in it.) The Tank holds 5 gals.. So over 20$ to fill up the tractor. LOL. It runs better on 93 then 87. It is smother.

[silversurfer13]

well im not an expert but i heard most cars nowadays can run fine on cheap gas(87) there are manufac that recommend higher..my 91 lude si said to run 91 or higher..i only ran 87 had no problems...had a friend who had a mid 90s nissan truck..put upgraded spark plugs and higher fuel and had problems..he took it in and the nissan place said that lot of cars or set up for running on crappy gas so when u put in higher octane and plugs its like ur overdoing it...05 vue here i run 87 have no problems and usually instead of adding additives i everyonce in a while will put in 91 to kinda clean it up some..does that make sense? p.s tho i love hondays esp sanota and accents who in there right mind would still one? lmao..not at u..ya know?

[allforhim325]

I've noticed people seem to think that their cars perform better on "premium" gas. I tend to find this extremely funny. In the area that I live in there is no requirement or testing the octane that you are getting. Basically, you could be getting the same old 87 when you're paying for premium. I'm not saying that everyone is off to rip people off, and I no don't go to gas town usa or anything, but people around here will traverse out of their way for a cheaper premium gas because thats what their car "needs" and still be getting the same thing as someone else who paid 30 cents less.

Okay, done ranting, just thought I'd throw it out there.

[SilverFox]

Well, one thing to keep in mind is that the engine's rating for fuel is the final say on what fuel you should put in the car. The owner's manual will usually tell you. As far as whether it runs better or not, it depends on the vehicle. It should be noted however that in some vehicles, a higher octane than what is recommended has also been said to hurt MPG. Whether this is true or not, I have no idea, but I do know that if it says 87, I will usually put 87 in it. If it says 93, then I will put 93 in it.

[SWilli]

"This compression ratio—somewhere in the neighborhood of eight to one—tolerates lower octane fuels (such as regular gasoline, good old 87 octane) without knocking"

The astra has a 10.5:1 compression ratio. I wonder if it would benefit from a higher octane gas?

[oseberg]

Are you guys still arguing about this?

This argument has been going on for years, and all those who believe that higher octane gas is good gas and lower octane gas is bad cause are wrong. There's nothing good or bad about either, they just have different octane ratings.

Some engines adjust the timing automatically with a knock sensor. An engine designed for 87 octane may advance the timing more if higher octane fuel is used, and that might improve the performance of the engine a little bit, but not nearly as much as increasing the compression ratio.

In order to increase the compression ratio you'll have to remove the cylinder head and shave it down a bit so that the combustion chamber is smaller. This change in compression ratio will probably blow your head gasket and/or wear out your main bearings because the rest of the engine wasn't designed for a higher compression ratio.

Using higher octane fuel and advancing the spark also increases the combustion chamber pressures and could cause increased wear on your engine, but probably not enough to notice.

Anyway, after 20 years of arguing about this crap, I'd think you all would be done by now.

[LakeAve]

It's your money, spend it any way you like.

[Djb200882]

The higher compression ratio the engine has the more octaine it needs. My old chevy is 9.5 to 1 and it pings with 87 octaine

[John Olson]

I think if you drive the car hard then it is wise to use a higher octane gasoline.

[fdryer]

Originally Posted by Djb200882

The higher compression ratio the engine has the more octaine it needs. My old chevy is 9.5 to 1 and it pings with 87 octaine

Yes but does this Chevy have a distributor ignition system or distributorless ignition, with or without knock sensing? Old school mechanical distributors with rotors, caps, and contact points never had anything but spring loaded centrifugal weights and a vacuum diaphragm for some semblance of advancing/retarding timing. Nothing was done for pinging/detonation prevention except maintaining timing though mechanical means. Those engines couldn't have ideal timing and still prevent pinging so it was more important about which octane was needed. Although those systems were state of the art back then, they still had a lot to be desired. EFI systems with totally electronic controls makes timing more fuel efficient as well as allow better engine performance to take advantage of maximim advance timing right up to detonation where knock sensors are listening for and tell the pcm to retard timing just enough to stop it. Electronics at its best for the highest reaction time to continously changing engine performance as governed by our right foot application - lead footed all out acceleration or granny driving. Knock sensors and the programs to deal with it automatically adjust to every octane number we put in our tanks to maximize engine performance but only up to a point. A car rated for 87 octane will not gain 10, 20, whatever hp (some think) will be gained by using higher octane fuel, only that the engine will run somewhat smoother because of the higher knock resistance accompanying higher octane fuel allowing maximum advanced timing.

Driving a car hard does not mean higher octane is needed. If that were absolutely true then every vehicle manufacturer is lying about octane requirements. I can stand on my gas pedal all day and run with the recommended 87 octane and still never make my engine detonate/ping/knock. I have knock sensing to prevent it and still make maximum power all because of electronic fuel injection and all that it implies. My engine has either a 10:1 or 10.5:1 compression ratio.

[danhammer]

Originally Posted by John Olson

I think if you drive the car hard then it is wise to use a higher octane gasoline.

Fiction

[danhammer]

Most of you guys do not know anything about gas and octane. That is fine.
For you just use what the owners manual states to use. In ALL of these cases it does NOT EVER PAY to use higher octane than what the engine is built to run on. That is FACT!

In FACT in most cases the higher octane fuel will burn less efficiently in an engine designed for lower octane and this will hurt your gas milage as you are sending some unburt fuel out the exhaust or some of it is finishing buring in the exhaust system where it does no good for gas milage.

The octane number determines how high you can compress the fuel air mixture before it detonates. High compression engines and turbo and super chargers require higher octane to prevent detonation from happening before the timing triggers the spark plug to fire the mixture.

If you have modified your engine then you should have a working knowledge of octane already and should know what fuel your engine requires.
If not ask your tuner.

[Tan97]

Originally Posted by danhammer

Most of you guys do not know anything about gas and octane. That is fine.
For you just use what the owners manual states to use. In ALL of these cases it does NOT EVER PAY to use higher octane than what the engine is built to run on. That is FACT!

In FACT in most cases the higher octane fuel will burn less efficiently in an engine designed for lower octane and this will hurt your gas milage as you are sending some unburt fuel out the exhaust or some of it is finishing buring in the exhaust system where it does no good for gas milage.

The octane number determines how high you can compress the fuel air mixture before it detonates. High compression engines and turbo and super chargers require higher octane to prevent detonation from happening before the timing triggers the spark plug to fire the mixture.

If you have modified your engine then you should have a working knowledge of octane already and should know what fuel your engine requires.
If not ask your tuner.

He does a good job of a general description. What most are missing is that this question is being applied to Saturns not all vehicles.

Saturns will run on just about anything, but the MPG changes if the gas is bad. There is very limited benefit for high octane in the Saturn engines. Money can be better spent elsewhere. If you swap Therms or Plugs to different degrees of operation then you need to start looking at octane levels.

I run a turbo in one vehicle and an SC in another vehicle. My Turbo will run on lower octane than the SC before detonation. The SC engine has right at 8:1 compression. If I put less than 94 octane in it I pull the pin so the engine retards timing to keep it from knocking. Less power and less efficency, but safe engine.

Change the spark duration and temp or compression levels and you need to change octane to run safely.

[RedGeminiPA]

I bought a new '06 Chevy HHR with the 2.4L and automatic. The manual recommended premium (91+), but said 87 was fine. I noticed a big difference between the two. For some reason, it was only '06 that stated this recommendation.

When I bought it (early production model - in '05), the EPA hadn't yet rated its mileage, so the sticker reflected GM's estimates. It was rated as 30 highway, which the EPA later (in '08 when revised) rated it at 28. I always ran premium, and I managed one tank average of 35 during a trip from here (Bellwood, PA) to Niagara Falls Canada and back - 512 miles on 14.5 gallons.

We run 89 in both of our 3.5L VUEs. I just don't trust many stations when it comes to their "cheap" gas (87).

[Johnlawrence]

I've detected people seem to reckon that their cars accomplish meliorate on "premium" gas. I lean to hit this extremely unusual. In the region that I elastic in there is no requirement or testing the octane that you are getting... so is there any other comparative replacement for the octane users........

[mattwithcats]

The oil companies have you both coming and going....

Not only does premium burn faster, it costs more....!

The higher the octane, the fewer the calories per gallon.
Hence 89 has less energy, and burns faster in the average car than 87...

Unless your car requires high octane, you are wasting your money putting anything other than 87 in.

Most gas comes from the same refinery, the "additives" is a quart of detergent, into a tanker load...

Recent tests (by a state college) revealed that about 40 percent of gas was mislabeled,
some was low octane (83-85) labeled as 87,
most was 87 in 89 or 91+...

Whether this was deliberate or accidental, just remember the state does not check octane, just the pump accuracy....

[Calavera]

I generally use 87 octane, but every once in awhile I'll get premium thinking it will help clean it out a little.