Gas: Is Higher Octane Worth The Cost? - The Definitive Answer... I Think

I agree with that also

the diffence between how much you paid for the gas and how many more miles you get from the high octane isnt worth it.

I usually fill my tank every 10k with high octane v-power from shell because sustained use removes the gunky build-up from your vehicle’s intake valves and fuel injectors, making your engine cleaner and protecting it from developing additional build-up. I then go back to 87 octane the rest of the time. I do get more gas mileage but the price is significantly more.

If the engine is designed to run on Premium it may also run fine on Regular. The anti-knock sensors adjust the timing to compensate.

The gas mileage may be similar with either fuel but the acceleration performance may suffer with the lower octane.

Hope this helps.

My manual suggest to use premium but not required and even though some of my friends use regular in the same model car, I decide to use premium, I don't miss the initial few dollar difference and feel much more comfortable that the car will perform better using the higher gasoline.

In 1974, cars had carburetors and distributors with coils. They had no ability to advance or retard timing due to predetonation....times have changed. But people will often hang on to old ideas, or listen to "myths" perpetuated on the internet.

Again, octane and mpgs bear no relationship.

now I drive a 2010 Mazda3 and I use the lower octane. I haven't ever put ethanol or the higher octane in it. I still don't know much about cars but I believe that is what is suggested in the owner's manual. I don't see any reason to burn extra money for basically the same milage. Maybe it would be beneficial every 10K for the engine as some have suggested.
As for the 1974 Cougar, I know what may have been good for it isn't so for todays automobiles.

On the car that required Premium gas if you put Regular gas it will get a bit less miles per gallon.

I did put regular 87 gas to Lexus GS350 or Infiniti G37 and I get a bit less miles per tank on combine city/highway driving, about 20 miles less per tank compare to Premium gas. On the highway only you barely notice the different, about 5 miles less per tank. Both car have 20 gallons tank and I usually fill up with 19 gallons.I guess in city driving stop and go the Premium gasoline help when you accelerate.

FWIW, I also use premium gas in my Honda powered lawn mower

with this comment.

Interesting findings, thank you for sharing

The octane rating of gasoline indicates how hard it is to burn. The higher the rating, the more resistant to burning. That is an over simplification but it will do for now.

Pre-detonation can be caused by the ignition timing or by heating caused by compression. If the knocking is caused by compressive heating then retarding the timing can not correct it.

I won't even start to list all of the damage that is done to an engine by knocks. The folks who designed the engine know what the engine needs. You ignore the manufacturer's recommendations at your risk.

i think if 87 wasnt good gas they wouldnt sell it at all . jmo

Here in the tri-state area of PA, DE, & NJ (USA) I've never seen a listing of lower than 87 where are you that has 85?

Anyway, My 2006 Saturn Vue recommends 87, and my 2003 Harley Road King recommends 91 or better. Most supreme here is 92 or 93 so that's what the bike gets.

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At higher altitudes, 85 octane is used for regular. As I posted before, my owners manual states 87 minimum, so I fill up with a mid-grade out there.

I was a mechanic for over 20 years. During that time I was also a service manager, a parts manager and I ran a service station for 5 years. I have read quite a bit about gasoline and the gasoline engine. I also worked 17 years for a company that manufactures fuel injectors and the rest of the fuel system, including the fuel injection computer.

I wanted to make this short, but it requires some explaining.

First let me explain how we got to the current Octane rating at the pump. During the "Gas Crisis" in the 70s, I was running a "Real" service station. At that time, ALL the automobile manufacturers used the "Research Octane Number" (RON) to specify what fuel the driver should use in a vehicle. There is also a "Motor Octane Number" (MON), but rarely did you see it mentioned (See Wikipedia for an explanation of the differences). Well, our Federal Government decided that people were being “confused” by having 2 octane ratings (even though probably 95+ % had never heard of MON). So they passed a “Regulation” that mandated that all retail outlets must now display a new rating called Anti Knock Index (AKI). This is determined by adding the RON and MON numbers together and then dividing that total by 2. If you look closely at the Octane stickers on the pumps, you will see this formula: (R+M)/2. Although I can’t guarantee that all stickers will have the formula on them, but I think it’s required.

So, what is Octane? Octane is used to describe at what temperature Gasoline will self-ignite. This self-ignition is what causes one type of engine knock commonly called “Ping”. Old timers called it “Valve Knock”, which is a misnomer, as it has nothing to do with the valves. But, it is directly related to the compression ratio of the engine. The higher the compression ratio, the more likely the engine will have knock problems. To avoid the knock problem, you can retard the spark timing. But retarding the timing will cause loss of engine performance. Extended periods of “Ping” can cause engines to self-destruct.

Diesel engines run on self-ignition. There are no spark plugs or igniters. Instead, they have compression ratios of about 25 to 1 (cars have anywhere from 7 to 12). This makes diesels hard to start in cold weather because the compressed air in the cylinder doesn’t get hot enough to ignite. Most diesels have pre-heaters that warm up the air before going into the cylinder. That knock you hear from most diesel engines is due to the fact that the fuel is self-igniting. FYI - Using gasoline in a Diesel engine will cause it to self-destruct.

To prevent knock, the gasoline manufacturers started adding anti-knock compounds such as Tetra-ethyl Lead (Very, very toxic. 1 drop could kill you. The lead in the emissions is why it’s outlawed) and Nickel compounds (Amoco used Nickel) and a lot of other chemicals were used. Adding a larger amount of anti-knock compounds allowed for higher compression ratios and using advanced timing – therefore more power. This is why you need different octane ratings at the pump. It’s all the same gasoline with different levels of anti-knock compounds added.

There is one other “Knock” and that’s called “Detonation”. Contrary to popular belief, gasoline does not “Explode” inside an engine. It actually burns at a very rapid rate of about 1500 ft. per second (close to an explosion, but not quite). Engine knock is the precursor to detonation, as ping can drive up the compression chamber temperature so high that the gas will actually explode – that’s why it’s called detonation. This will punch holes in pistons and will cause engine failure.

Today’s fuel-injected cars can actually “tune” the engine to the grade of gas you are using. By advancing the ignition timing while you are accelerating, the computer will “listen” for a signal from the “Knock sensor”. As soon as that signal is received, it will retard the timing until the signal stops. Most computers will have the settings stored in memory. The computer will change the settings as time goes on. Older cars had volatile memory, so the settings were lost if battery was disconnected. Most newer cars have non-volatile memory that will keep the settings if the battery is disconnected and the car won’t have to re-learn the best settings.

There is a lot more to electronic fuel injection than people realize. All kinds of sensors are tied to the computer, whose main job is to control emissions. Secondary jobs are fuel economy and power.
An older carbureted car with no computer, would definitely show way different mileage results with different octanes (unless you knew where to set the timing for each octane rating).

Modern, fuel injected vehicles will adjust ignition timing and fuel mixture ratios to get the best emissions, economy and power. That’s why “canadianation” came up with his results.

Thanks for posting this. It was easy for me to follow and it's quite interesting.

Jonathan (aka JM)

Thanks, Jon.

I tried to make it short, but - oh well.

There are a lot of misconceptions about gasoline. I just wanted to be sure that people think twice about spending money for premium. canadianation actually took the time to check if it was worth while for his vehicle - it wasn't cost effective.

Now let me blow-up an idea about "Brand" name gas.

Most non-company owned gas stations are NOT required to buy from the brand that they display!!! So you don't always get Shell or Exxon or Texaco or whatever the sign says. And there are very few company owned gas stations around any more. Check out the "Business License" inside, next time you buy gas. Bet it's a local or reginal business and not a BIG NAME owned station.

It used to be that the Oil Companies owned all the outlets (well most, that is). After the oil crisis, they started selling them off to reduce costs, as things got very competitive and they started merging. Basically the sign out front says "We take this 'Oil Company' credit card"!

There is no guarantee that you are getting the brand of gas that is on the sign.

Buyer beware! This is why I buy my gas at Sam's club. Much cheaper and I haven't gotten any bad gas yet, in over 10 years.

There is no benefit from the use of higher octane gas when not needed. In fact, years ago when Sunoco had their "custom blend" pump they had a setting that was "below regular". (If I remember right, and I likely do not, "regular" at the time was 89 octane and the "below regular" was 87). I had been using regular but tried the "below regular" to save a few cents and see if it would work. I had been keeping very accurate mileage records and I actually saw a measurable improvement in mileage when using the lower octane gas in my old VW fastback.

There certainly are many engines that need and will preform better with higher octane gas. But if your owners manual says to use regular gas rather than premium, you are likely better of doing just that. You're not doing your car a favor by occasionally "treating it" to higher octane gas, although you are making the oil companies happy.

I remember my first car, 1969 AMX 390. About every two or three months I would go out to the airport and get some 120 octane avgas. When it was really the good stuff. And did I really have fun driving back home. It really did make a difference, and yes it did get me a ticket or two.

Though now days with this watered down stuff say call gasoline, I would have to wonder. You can buy only so much 104 Octane Boost.

And I thought my dad was nuts for always talking about the good old days. Just like my son thinks I am nuts now. His time is coming.

now that we got part 1 of the gas question settled, are there any major differences between the gas stations??

As I stated earlier - it's getting harder to tell.

Although, there are several articles online stating that there is not much difference between the brands.
See: http://ezinearticles.com/?Is-There-a-Difference-Between-Gaso...

http://www.mcall.com/all-warrior-051404,0,6518560.story

There are several more articles out there. A lot refer to the report that Consumers Report did in 1995 (or 96) that found miniscule differences between brands. They all have to comply with EPA regs and that's what they do.

I agree with a lot of the articles stating that most people just have a "Gut Feeling" that their brand out performs another.

I periodically add some "Gumout" to my truck's fuel tank to help clean the injectors, even though it's probably not needed.

Something to think about:

When was the last time you saw a "Brand Name" tanker truck going down the highway, or off loading at a Gas Station?

All most all of the brands here in NW Ohio buy their gas from just 2 refiners, BP and Sun. There is a difference between the brands when it comes to additives, the delivery company adds the proper stuff to the tanker before it's filled. But the gasoline stock itself is all the same. It all has to meet EPA requirements, as another poster has already stated, so there can't be much difference. It's kind of like Sprint Cup Stock Car racing, take off the decals and the cars are all the same.

We try to use ethynol free gas whenever possible. Sometimes we use a higher octane. We get better mileage with both.

That's a new one to me. Almost any fuel you buy (of any octane) will have detergents added to it to keep things clean. As someone posted earlier, if you have concerns about keeping the engine clean you can always use a brand that meets the Top Tier standards but running 91 octane through an engine that requires 87 is a waste of money.

jackj180,

Since the additives are pretty toxic, I don't think that they are added in at the delivery terminal by the driver or by anybody else. Besides, one boo boo (too much or too little) that happens and then that load happens to be sampled by the state weights and measures folks and there is a big stink. The gas station could be shut down and criminal charges could be brought.

Depending on the state, the weights and measures folks come around every 6 months to verify that the pumps are reading the volume of fuel dispensed acurately. Pumping more than is shown will get the pump tagged for repair. Pumping less than is shown will get the pump red tagged (stickered) and you will not be able to sell from that pump until it is repaired/recalibrated and rechecked by weights and measures. Of course, there is a +/- that is allowed, but it's not much on the "short" side. They also take a sample of each grade of fuel that is dispensed and it is analyzed in a lab for Octane Rating and to verify that there is no Lead.

There are just too many things that could go wrong that could cause legal problems with the state and federal governments. Therefore, it's added before it goes into the huge storage tank or pipeline.

Most gas, at gas stations, comes from a nearby tank farm that is fed from a pipeline that is tied into a refinery. It is just too expensive to truck gas any distance, and the buyer pays the delivery charge which increases with distance.

When I ran a Sunoco station here, I visited the Sunoco terminal near Richmond (aka Tank Farm). Sunoco was actually dyed Blue at the time. I got a quick tour and they explained that the gas they distributed came via pipeline from the refinery in NJ and that there were other brands in that pipeline as well. The pipeline actually used slugs of water to separate the different loads going to different terminals. The hardware that removed any water that managed to get in their line was 100% effective. They had a final filter on the line with a glass monitor and the gas was blue, so I know that they were not adding anything to the gas there.

I blame NIMBY on the current mess with gasoline distribution. Terminals have to be built (if allowed) away from any housing developements and have to meet all kind of regulations. Try to build a refinery and all kinds of groups will oppose it.

But gasoline demand is down, due to better mileage cars being on the road today. There is a refinery in Yorktown, VA that has shut down due to the lack of demand here in the U.S. A lot of other refiners are actually shipping their gas and diesel overseas.

It's a very complex system that gets the crude from the well to being gas in your vehicle.

Thanks for posting this. I always use 87 as manual shown.

very useful analysis thank you

Some cars require certain octane ratings, so make sure to check that first!

The car's manual states "premium fuel recommended but not required". I started out using regular gas all of the time. During the first 38000 miles had two oxygen sensors to go bad. The service department stated that the regular gas caused the sensors to fail, and would fail again if i continued to use 87 octane, so I switched to the 93 octane. No trouble since the change but the fuel improvement does was not enough to compensate for the cost.

metricman,
Thank you for correcting me on where and when the additives are added to gas. I was basing my statements on the fact that the trucking company that delivers fuel to all of the gas stations in my area seems to also be the only trucking company at the two refinery's depots. Also the truck driver who told me about adding the additives to his tanker before filling it obviously didn't tell me the truth. I have to admit that it didn't make sense to me at the time. Add 5 gallons of additive to 30,000 gallons of fuel and you'll be taking about pretty low concentrations.

In general, higher octane fuels vs. gas mileage increase is not enough to offset the increase in the fuel price. This is assuming newer cars with electronic adjustable ignitions (nearly all cars in the last 15 years). With conventional ignition systems there is no benefit at all. Always use the fuel grade suggested by the manufacture.

Some cars run better off higher octane gas, and some require it. Different brands from different gas stations affect it to.

For example Arco gas makes my car ping at high speed and it runs out faster. Chevron gas does not ping and last longer per tank refill.

BTW I run midgrade gas.

This is going to be different for every vehicle. Let me tell you about my FJ Cruiser. It was designed for premium fuel and has a sticker on the inside of the fuel cap cover that states it needs to be used. However, Toyota later made a statement to the effect that we could safely use regular unleaded fuel, but would experience decreases in fuel efficiency and performance.

For city driving, premium fuel pays for itself. For highway driving, it is close, but it does not pay for itself. But with the small 19 gallon fuel tank I have, it is nice to get the extra few miles, especially if off road or in other secluded areas.

The performance drop is noticeable, but not an issue most of the time. Altitude hits the performance much worse than lower octane fuel. I'm not sure I would want to stack the two if I were driving over the 13,000+ ft. passes in Colorado.

So far, high octane has cost me about $2000 on my 2000 Honda Accord EX-V6, which audibly knocks if I use lesser gas.

Next time I'm buying a car with a lower compression engine.

If the manufacture recommends regular go with it.

My car takes regular, my motorcycle requires premium, with the cost of premium jumping twice as fast as regular it may soon be more economical to run the car

I have a 2004 Jag that requires the higher grade and I have done that. Jugs need the higher grade, in Europe takes 95 or 98, but in many countries like Canada they adjusted to run on 91.

You are right premium in (Southern Ontario) Toronto is 16-18 cents higher than regular.

And that's 16 cents a LITRE or something like 65 to 70 cents a gallon.

Yes is per liter.

Interesting thread, but I can't believe no one mentioned the Tappet brothers!

http://www.cartalk.com/content/premium-vs-regular

Unless your car is tuned to run a higher octane your wasting your money. A higher octane burns at a slower rate than a lower one. thus the timing of the engine needs to be adjusted to compensate for this. Run what your car was designed to run on. Just use good gas and not the el cheapo gas station gas and you will be fine.
Only use top tier gas stations.
http://www.toptiergas.com/retailers.html
A nice little informative video.
http://www.toptiergas.com/

Good info, but,
I did not see Sunoco listed at US side, though it is at Canada. Do they provide different formula?

That's interesting even though I buy my gas from either Costco, Flying J or Ultramar

The only reason to buy high octane gas is if your car has a high compression engine. Any modern engine with a compression ratio of less than about 9.5 : 1 will run fine on regular grade gas.

No

With gas prices, in general, down about 17 cents/gal locally in the past 3 weeks we can smile a tiny bit.

One of my friends sent me a map which showed the tax (fed, state, county, local) on gas for all 50 states.

The 5 highest states in taxes on gas were:
NY, CT, CA, MI, IL

The 5 lowest states were:
AK, WY, NJ, SC, OK

The data was from January 2012

One time while eagle watching, I was driving to my next location when I neglected to watch my gas guage and ran out of gas. I just happened to have 3 small bottles of heat gas treatment in my trunk. I put them in the tank and the car started right up. I couldnt believe it but I made it 7 miles into the next town where I filled up. The engine service light came on and I had to replace my oxygen sensor, but I did not walk.

Premium or high Octane gas is required usally in high compression engines and or turbo charged cars.
I once had a turbo intercooled Volvo and noticed a difference between the two gas grades in performance.
On regular vehicals i have noticed better milage but at the higer cost of premium gas works out to about the same.

They are still on the rise up here. And I have seen a variance of at least 10 cents/gal at the same brand of gas.