from jstand6 in another thread:
http://www.protegeclub.com/forum/sho...5&pagenumber=2

search for the string:
"excellent explanation of pinging"

And here is the link he is referring to:
http://www.msgroup.org/Contrary/NEG037.html

and right back at you heh =D

I dunno. It's off the 'net. Believe what you want. I am going to believe it though unless someone else can prove it wrong.

Mak, how much better is the fuel mileage? Is it worth the extra money per litre? And are you sure it is attributed to the change in fuel, and not a change in quality of oil, maturity of the engine (breaking in), driving habits, driving routine? I mean have you ever gone back to 87 after you found out you had better economy?

 

well, those links have very good information in them, and i agree with what they say, BUT they do not say why it is "bad" to run higher octane gas. that link that goes to a commentary by Larry P. only says that if you are running on lower octane gas, and your car starts pinging, it is time to do some maintenance. (it also is talking about older cars (1974 volvo?) and motor cycles) i still haven't read someone showing good information what bas things can happen from running higher octane gas. and i still believe that higher octane gas burns in a more predictable way, and just as completely as lower octane gas. AND, i've stated this before, octane only prevides a measure of safety against pre-ignition due to compression. (it won't combust from being compressed, only when ignited by the spark plug)

 

It's not "bad" to run high octane gas. Just a waste of money. And it will actually reduce your performance, although not enough for you or possibly even a dyno to notice it. Why spend the extra money per gallon for nothing.

And it has in the past been a problem for some engines. The Ranger 2.3L is well known to have issues with running higher octane fuels. They cause long term performance loss issues for the engine.

 

This is what I gathered from reading it.

It is bad because:
a) You get excess build up of carbon that you would not get with lower octane gas. EVEN though the higher octane gas supposedly has more cleaning agents. It's better not to have the excess carbon in the first place. (note long term performance loss)

b) You may be masking a problem. If you are, and have been running 89 or 91 for let's say 6 years (warranty is gone so you know things are gonna start cropping up ;P), and your engine starts having some problems, where it would ping with 87 gas. But since you are running higher octane, you don't notice it. Kiss those bearings goodbye.

Why would higher octane burn just as completely? The octane is to help resist burn, which is not what you want. I don't know enough about the octane numbers to do any calculations, so maybe 89 will burn as cleanly as 87 on most if not all sparks. But you don't know. Isn't it safer to run a lower octane?

Predictable? How so? Any proof of that? Or is it just something you want to believe?

I think there is more potential harm than their is potential benefit to running higher octane gas.

BUT.. again.. just my opinion based on stuff i've read on the 'net =).

 

"Best" octane rating has been debated at length in other threads. Can we please not re-hash everything again here as it is not related to the topic of this thread... unless someone has established a connection with the engine 'rattle' and use of certain octane ranges... If that is is the case, please post that information here. I am following this thread to keep abreast of the 'rattle' topic, not hear endless opinions/squabbling about what ocatane level is good/bad etc. for the Protege engine.