87 or 89 Octane 2AZ FE age old question

[JComerford]

Anyone out there... Have advice for 2AZ FE 2.4L VVTI engine octane? The owners manual says 87 octane, but the TOY dealer service guys say 89 octane burns cleaner, slightly smoother, better fuel mileage? I've read articles that say using over 87 octane in an 87 engine just throws off the sensors/computer and you get NO benefit and may be not good for the engine, that you are wasting your $. Any actual facts/experience, does it run 'better'? My wife's subaru (2.5 wagon) service department also recommends 89 for her car-says it keeps pistons/combustion chamber cleaner?

[JetspeedCamry]

Its 2AZ-FE not, 2AFZ...

And yes, 89 wll burn "better", cleaner etc. It's not critical though. You can use whatever you can afford. It'l run just the same on 87 than it will with 89. However, i try to use as higher octance as possible that I can afford at the time (98 here in oz).

[ModifierMR]

I Filled my tank with 93 Octane or whatever and my car ran fine. No problems. And i did see an improvment in the miliege. My mechanic says that gas stations where i live have been adding a lil water to the gas. So 87 Octane isnt really 87 at all.

But 93 or w/e i used which was the highst i could get, was $60 to fill up!

with 87 its usually around $32

[JComerford]

Thanks for the engine correction, and the opinion. Nice Cam!

[kenny1773]

Use 87 in a 2AZ-FE

89 does not "burn better"
93 does not "burn better" either

Higher octane gas is actually LESS volitile and more resistant to burning.

Higher octrane CAN buy you a slight advance on timing in engines designed to do so. I doubt the 2az-fe is one of those engines. The 1mz-fe is though.

All you gain is efficiency *IF* the engine is programmed that way, advance the timing, get a SLIGHT (ever so SLIGHT) more bang when the spark hits.

There are the same number of BTU's in a gallon of 87 as there are in a gallon of 89 and 93. BTU's are how you measure the energy in each gallon (or how you determine the "work" that each gallon can perform), without higher energy you are not getting any more "work" out of the gallon.

*IF* 89 had more BTU's per gallon, then it would be possible to gain more MPG, this is just not the case.

I will note that some top shelf higher octane gas will have more additives to keep your fuel injectors, etc cleaner, but the EPA has mandated so many cleaners in all forms of gas that I think even the cheapest 87 out there (in a major city that calls for reformulated gas, like where I live) will be above the min level to keep your shit clean. Run a fuel system cleaner every oil change if you are really worried (on sale at walmart for $2-$3)

I remember a buddy of mine had a 95 Taurus SHO and him reading a big long discussion about the SHO requiring 93 octane. Many people actually showed just as good of quarter mile times with either and argued it was a waste of money to buy 93.

but YMMV - every engine is a bit different. It is possible that your engine has something wrong with it and will require 93 in order to run without pinging.

[JComerford]

Originally Posted by kenny1773

Use 87 in a 2AZ-FE

89 does not "burn better"
93 does not "burn better" either

Higher octane gas is actually LESS volitile and more resistant to burning.

Higher octrane CAN buy you a slight advance on timing in engines designed to do so. I doubt the 2az-fe is one of those engines. The 1mz-fe is though.

All you gain is efficiency *IF* the engine is programmed that way, advance the timing, get a SLIGHT (ever so SLIGHT) more bang when the spark hits.

There are the same number of BTU's in a gallon of 87 as there are in a gallon of 89 and 93. BTU's are how you measure the energy in each gallon (or how you determine the "work" that each gallon can perform), without higher energy you are not getting any more "work" out of the gallon.

*IF* 89 had more BTU's per gallon, then it would be possible to gain more MPG, this is just not the case.

I will note that some top shelf higher octane gas will have more additives to keep your fuel injectors, etc cleaner, but the EPA has mandated so many cleaners in all forms of gas that I think even the cheapest 87 out there (in a major city that calls for reformulated gas, like where I live) will be above the min level to keep your shit clean. Run a fuel system cleaner every oil change if you are really worried (on sale at walmart for $2-$3)

I remember a buddy of mine had a 95 Taurus SHO and him reading a big long discussion about the SHO requiring 93 octane. Many people actually showed just as good of quarter mile times with either and argued it was a waste of money to buy 93.

but YMMV - every engine is a bit different. It is possible that your engine has something wrong with it and will require 93 in order to run without pinging.

Thanks for your great clarification and help! So other than additives whatever the owners manual says for the engine-maybe not the shop boys! THANKS!

[AznVR4]

I use 93 and when i went back to the toyota dealership wit a clicking/ rattling sound comming from the passenger side, they accuse me of using cheap gas, and blame my problem on the gas. i start saving up my reciept now to prove them wrong that i been using 93, i had never used anyting lower than 93 on any of my cars. But my friends use lower octane and i feel the difference between the pick up of the car when i drive it.