I have always put middle-grade gas in my 06 4-runner sport. Not because I am educated about what the difference is between the grades (octane this or that) or how higher grade gas may help my rig or not. Rather I do this because, like many Americans, I have a good job and the cost wasn't a big deal. I figure higher grade must = better for the car. Since I didn't know better, I figured I would settle for mid-grade (i.e. not the best or the worst assuming once again that premium must = best and regular unleaded must = worst). I know this sounds lazy and naive, but I'm sure its a behavior shared by many.

So obviously as gas prices continue to go up and I stand to save $5-$8 per fillup, I find myself more motivated to ask myself why I am buying gas that is more costly than regular unleaded. So I put this out to the forum...

1. What grade do you use in your 4-runner and why?
2. What really is the difference between the three grades?
3. When DOES it matter what grade you use?

I also have a sports car that I have always filled with premium. Once again, on the simple impression that this car deserves "the best" and premium must be "the best"

Educate me folks!

JC

P.S. - is anyone else tired of hearing how bad the economy is and the devastating housing market/gas prices only to then get bogged down in more traffic than ever? Not just people trying to get to work, but seems like more people than ever are still well-off enough to spend time at the luxury spots, or eating out at fancy restaurants. I just think its funny because you hear how bad it is on the news every day, yet at the same time urbanites are still out in force driving their HUGE hummers flooding the Costcos and Malls, sipping $5 lattes, etc. Are things worse in other cities (I am in Seattle area).

There are many business suffering and a lot of people and family's. IMO this $4+ per gallon stuff has not even hit the trickle down effect hard yet.

As far as gas , I always run 87 oct in my 06 V8 Sport. Runs perfect. I also watch what stations I buy gas at . I always go to a friends Mobil station where he strictly buys Mobile fuel . Many stations can buy cheaper "generic gas" .

No expert here - but the book calls for 87 and it runs fine on that. If I were to start to hear any engine knock would move to 89.

JC,
This one post has 172 replies and most of the collective wisdom of the forum (or collective BS )
http://www.toyota-4runner.org/showth...&threadid=8088

This one has 108: http://www.toyota-4runner.org/showth...threadid=21910

If you skim through you'll get the idea...

On your PS, I am in SWFL the heart of the real-estate garbage. We were 1st, in the deepest and we're beginning to see signs of the light at the end of the tunnel. I have been to Atlanta a few times recently, much better there...

The quick answer on your questions:
1)93 octane, slight improvement in mpg and responsiveness. Provided the premium in price is 8% or less for me it's worth it. In my market the cheap gas is only 20 cents/gallon cheaper.
2)The primary difference is resistance to ignition and rate of burn.
3)When you want max power run premium. On the T4R it takes 4-5 tanks for the computer to take full advantage of the higher octane. On your 'sports car' it depends on what it is as to whether the premium fuel is required. If it sits for extended intervals I recommend sticking with premium. For some reason the shelf life of premium seems to be better.

87 Octane fuel is just fine for your 4Runner - and most other properly maintained & tuned cars/trucks on the road. The vast majority of cars do not need mid-grade or premium fuel under most normal driving conditions.

High-test is only necessary for cars with higher-compression engines that require it (Corvette, some Cadillacs, Shelby Mustang, BMW, etc.) -- or if you vehicle knocks constantly on lower-grade gasoline.

My V8-powered 2008 Mustang GT runs okay on regular and only exhibits some minor pinging under hard acceleration. Almost every car has a "knock sensor" that will temporarily cut back your ignition timing if you happen to use cheap fuel, however. This prevents pre-igntion or 'detonation' and helps to prevent engine damage; but chance are that it will act before your ears can pick up the sound of the air-fuel mixture igniting before it is supposed to.

If you regularly use gasoline with too low of an octane rating, your fuel mileage may suffer a bit - negating the per gallon savings at the pump. It varies from car to car.....so be careful!

I have driven many types of vehicles and know that some cars are much more sensitive to this than others. Besides, if you can afford a new Lexus or BMW, don't moan and complain about having to fork out so much money for gasoline. Your whining will most likely fall upon deaf ears!



P.S. Diesel engines, which run on "compression ignition" instead of by spark, require the fuel-air mixture to ignite on its own (no spark plugs). Diesel fuel is measured by cetane - which is the opposite of octane; since those engines run by "knocking" that would destroy a gasoline or spark-ignition engine after a few miles. Just an interesting tidbit for you today.


-- EDITED FOR CLARITY --

i used Premium exclusively for the T4R for two years and then switched to Regular. never experienced any difference at all between the two.

i was using Premium for the Pathy and switched to Plus and again, haven't experienced any difference between the two. Premium is now below $4 here in NJ so i may start filling up again with Premium. the difference between Plus + Premium is only 10

I fill up with 87. Every penny counts, and I have a good job and could afford premium, but to me its a waste of money, but please don't take offense, that's just the way I see it. My rig runs perfect on 87.
I use premium for my outboard and lawn mower because its non-oxygenated (4-stroke 15 hp Yamaha sips fuel so the extra cost is negligible) and recommended by the manufacturers.
The roads are just as crowded as ever getting to work, but after work and even on weekends the traffic has thinned somewhat. In MN, lots of people have cabins up north and so the migration begins around Friday at 2 pm north and back to the cities Sunday around 4 pm. Those are just as busy as ever also, and also the boat gas and other gas needs are still in full swing.
It has an effect on some, but quite frankly food prices rising is more scary. We all need to eat, but there are ways to counter gas prices and still survive.