5S-FE fuel?, What fuel to use? Options

[UVZ164]

Hey guys, I'm kinda new here and not sure if this is the right place to post this.

I did a search but couldn't find the specific answers I wanted so I thought i'd ask.
I live in Sydney Aust and the fuels available to us are: E10(10% ethanol) 91 octane, and regular 95 and 98 unleaded.
I recently bought a ST204 ZR which is the equivalent to the American GT. It runs the 5S-FE.
The guy I bought it from told me to steer clear of the E10 as it will ruin the engine. As my wallet isn't that deep I decided to give the cheaper E10 a go.
After about a month and a half of running the E10(i'm assuming the previous owner used 95) i'm beginning to hear a noise almost like tapping when I rev the engine above 3k rpm and just let it decrease naturally. As it never made this noise before, could I be right in assuming that the E10 is doing something and possibly ruining the engine? The owners manual states that 91 octane is as low as you can go but it doesn't say anything about Ethanol.

Thanks in advance,

Reece

[richee3]

I lol at the threads and the general misinformation about octane ratings. Octane resists detonation, not add power. You don't get "more fuel" in your fuel by pumping a higher octane. Galcobar covered all the bases, 100%. To further his point, I have to pump at least 91 in my IS 300. Why? Compression. The 2JZ-GE isn't a super high compression engine, but it's not exactly low compression in NA form. When I pump anything less than 91, the ECU has to compensate by pulling timing, which throws a CEL, until so much timing is pulled that the car can barely idle. And if I stab the gas with lower octane fuel, I run the risk of pinging and causing serious damage.

By the same token, pumping anything higher than 87 in a Celica is throwing money away because it won't make any difference. It doesn't burn any hotter, it doesn't burn any cleaner, all it does is resist knocking.

I misspoke in my last post. I said use "the cheapest fuel," but I didn't mean run utter crap in your car. I meant whichever octane rating happens to be cheapest. There is a definite difference between top tier fuels and octane ratings. But, as I said, Galcobar has already covered that better than I can. Just Google top tier fuels and you'll find everything you need to know.

Main point- OP, don't worry about what the last owner of your car told you about running premium fuel in your car. If it actually does happen to have an issue, it isn't related to the octane rating of the fuel you've been using.

This post has been edited by richee3: Oct 20, 2011 - 6:55 PM