Aniki010

I had a question for anyone that can answer it

In the manual it states that you can use the regular fuel for the protege5. Do you guys think it is worth usint the plus or premium fuel? I don't want to be wasting money on gas if it is not really gonna make a difference. GAS in the BAy area CA is sooo expensive!!

THanks for always responding soo fast fellas

JJB

this is one of those topics that starts an argument on the board

The short of it is, the car will run fine on regular... and some people use that. There are some (myself included) that run higher octance gas. Why? the car runs fine. It seems to come down to personal choice.

For more details on octane/opinions/etc you might try a search on "octane" it will turn up a couple of good threads.

You'll get the same type of debate when you ask if synthetic oil is what you should be running... opinions are varied as brands and types of oil.

kc5zom

You know, administrators should probably just start locking these threads when they see them. Its always an attention getter.

Oh yeah, I run regular. You will actually see a slight performance decrease using higher octane fuels (nothing noticeable) since they take longer to ignite.

Aniki010

Yah thanks for the replies.

I have heard from countless numbers of mechanics that if you use high octane from the beginning and only high octane it can be very effective but if you use a lower octane fuel even once that it won't make a difference using either. I think what that means is when its a higher octane the fuel is much more filtered and cleaner therefore if you use a fuel that is less "clean" your car piping has been "dirtied"therefore even if you use the higher octane after you have gone down a grade or two it won't make a difference. I am not sure exactly so don't quote me.

But thanks anyway i think i will do a search

kc5zom

Anik,

That is a very common misperception about premium grade fuels. They are not cleaner than 87 octane fuel. All fuel carries detergents to keep your engine clean. The engineers at Mazda know this and they recommend using 87. The whole point for 89 and 91 octane fuel is for customized or highly tuned engines. These engines require that the fuel resist ignition more than our 2.0L. The only component on your car that will remember anything about the fuel you used, unless it was the crappiest dirtiest fuel ever, is your ECU which stores information to allow itself to run at optimal power, emmisions, and fuel consumption levels. This information is lost whenever you reset the ECU (or battery power is lost).

When you want to shift to higher octane fuel is when you have been tuning your engine. The most common reason is to offset the dangers of preignition with a higher compression setup. You might also want to shift to a higher octane fuel if you notice your engine is knocking. Otherwise you are just wasting cash.