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Premium gas in Protege

I always switch to Premium gas during the summer. The car runs cooler, has more power, idles better, and gets better gas mileage. When temperatures get above 90F, carbon buildup on the top of the piston in high mileage cars can cause detonation in the cylinder due to the temperature of the engine and the additional compression ratio. Even new cars can "ping" with pre-detonation due to summer heat. Since the Protege holds such a small amount of gas, it is well worth at least trying Premium gas since it will only cost you about $4.00 per fill up and you will be very happy with the results and so will your Protege. I tried the middle grade but the results are more impressive with premium. If it's good enough for German performance cars it is good enough for a real quality car like my Protege. Up to you of course.

I am not an engineer, so I will leave the technical explanations to those who have more appropriate credentials on the subject than I do. There have been several posts on this forum regarding the benefits of premium gas in Mazda Proteges (or is it Protegi!). There are some who say there is no benefit and others who say there is with numerous explanations as to why.

How much more power and fuel economy are you getting? What is the summer like where you are? What brands have you tried?

As an accountant, my ultimate question is: Is the improvement from premium in a car that does not require premium offset the extra cost of premium? If fuel economy increases 10% but premium costs 15% more, it is not worth the extra cost.

If it runs so much better why are you not using it all year round?

Good question. Where I live it gets up to 100f+ during the summer. The heat is what can cause the pinging in your engine especially in stop and go traffic when your engine gets up to max temp. You may also notice a loss of power due to the heat. I have heard almost new cars pinging when it is really hot and traffic is stop and go (I like to drive with my window down even though the AC works fine). Premium gas stops the pinging and helps the engine run better when it is hot. During the winter when it is cooler the pinging is not an issue. I put use premium ever so often during the winter also. I do notice a difference summer or winter. The main issue is price. When gas was really cheap, filling up the Protege with premium was no big deal but now that gas prices are higher, I will switch back to lower octane but I would not if gas was cheap like it used to be two or so years ago. I do also suggest that you DO NOT USE ehtanol gas if you can find reasonable priced straight gasoline of any grade. Ethanol blend (10%)gasoline gets about 10% less mileage and provides 10% less power.Also if you let ethanol sit in your gas tank for over 6 weeks it will start to go bad and could gum up your engine.
Here is a test you can do. When it gets really hot, and you have been in slow traffic, lower your front windows, find a road next to a long wall or buildings then slow down, give it gas, and I predict you might hear some pinging. Gas ain't what it used to be.
Hope that helps.

I have noticed a significant difference in gas mileage between winter and summer. I credited it to a combination of the additives required to be put in gas creating summer and winter gas (at least in the Mid-Atlantic states) and the reduced traffic congestion.

People, can we all please get along?
If you disagree with someone just let it go.

High octane fuels burn slower than lower octane. Under normal conditions they are recommended for high compression engines, engines that have a power adder installed (turbo or supercharger,) or engines that have a high initial, or quick advancing ignition timing. After modifying and installing a quick advance distributer in a previous car I once owned, I had to up the octane from 87 to 91.
Under "normal" conditions, running too high an octane in an engine that is not designed for it means the burn will be incomplete and a portion of raw fuel, mixed with the spent gasses, will be dumped into the exhaust. In modern naturally aspirated street engines this has the effect of causing the emission system to work harder to clean the unburned fuel before reaching the tailpipe. In the long term it can harm O2 sensors and especially the catalytic converter. The cat will get hotter and its life will be reduced... however slowly.

With that said, if you are experiencing pre-ignition you should switch to a higher octane fuel, or perhaps try a set of colder spark plugs, which could have a similar affect. Colder plugs are often utilized in an engine that runs a super, or turbocharger to keep pre-ignition (pinging or run-on) in check.

Have you tried running mid-grade, usually 89 oct, fuel? A bump in octane of 2 points might just do the trick. I know that my 3 (2.3L N/A) has always run worse in the Texas summer heat. I have tried running higher octane, a tank here and there, and did not notice any difference in mileage or the way it runs/idles during this time of year.

Just a quick clarification, pre-ignition happens before the spark event and will destroy an engine in a matter of a few revolutions; given you referenced pinging (which by definition is detonation) later on, I believe you meant to write "...if you are experiencing detonation..."

Well, I'll leave a couple of facts and and my own observation.

The Mazda Protege owners manual says 87 Octane is "best". (you may check for yourself).

Summer and Winter blends are different with Summer blends typically delivering better mileage. (Feel free to search/learn to fish).

My 2003 Protege5 runs fine on 87 octane fuel. Yes, I tried some 91 octane and did not see any appreciable increase other than my cost of operation.

Run whatever you prefer.

Quote:

Originally Posted by shipo (Post 168765)

No sir, but I did forget to define run-on or "deiseling" which happens on carburetted cars that still have a fuel supply avaiable after the ignition is shut off, but has "hot spots" that keep the fuel burning. Since the engine usually runs in reverse under these circumstances, THAT can ruin an engine in short order.
Pre-ignition, as I understand it, is the ignition of the fuel prior to the spark plug firing (we agree to this point) due to hots spots and/or low octane fuels used, and that causes the pinging. It's very hard on the engine bearing, etc, but I have yet to see or hear of an engine dying from it in just a few revs. A higher octane fuel would is less likely to be ignited under these conditions, hence reducing or eliminating the "ping."