octane for 1MZ-FE engine

[tylerho]

You may get this question all the time but what octane should I use on my 1999 v6 camry. It already has 127,000 miles on it, recently i put in 89 octane gas from chevron with lucas oil fuel system cleaner. So should i stay with 89 or go to 91 octane. One more thing is arco/bp gas any good.

[fenixus]

stay with top tier gas stations and you will be OK. those would be all major fuel suppliers like Shell, BP, Exxon, Chevron and a few others uncommon to my region.

manual recommended is 91 octane to feel the full capabilities of V6 engine at its 10.5:1 compression ratio. but we all know that a wallet has a word to say too so any grade (never go below 87 though) will not harm it, it might just feel less powerful with 87 in tank.

I actually tend to fill my V6 up with Shell Premium fuel (93 octane in my area) to have some fun when I want to

[cf99]

This is from the '01 manual but probably the same:



In some cities all gas stations get their base gasoline from the same pipeline, and then mix in their brand-specific additives. So if some gas is bad, all gas is bad.

[fenixus]

worth mentioning the RON calculated octane numbers are used in Europe (and Asia I think) while North America uses AKI calculated octane numbers.

so 87 AKI octane = 91 RON octane
and 91 AKI octane = 96 RON octane

[pmesfun]

I tried 93 for about 3 fill ups, but didn't notice any change in power or mpg. Also, gas prices are too high to use 93. Don't even put in a full tank anymore.

[fenixus]

true, that's the wallet side of this story it's getting harder and harder for me too to stay with premium fuel on this car ... good thing I don't drive it too much, so can't feel the real problem.

my wife's 5s-fe runs on regular 87 fuel, she drives further distances daily than I do. ... but on weekends it's just pure pleasure for me to take V6 for a ride together and have that Hulk kick under my foot

Originally Posted by pmesfun

I tried 93 for about 3 fill ups, but didn't notice any change in power or mpg. Also, gas prices are too high to use 93. Don't even put in a full tank anymore.

[pmesfun]

Originally Posted by fenixus

true, that's the wallet side of this story it's getting harder and harder for me too to stay with premium fuel on this car ... good thing I don't drive it too much, so can't feel the real problem.

my wife's 5s-fe runs on regular 87 fuel, she drives further distances daily than I do. ... but on weekends it's just pure pleasure for me to take V6 for a ride together and have that Hulk kick under my foot

Yeah, I've been starting to drive aggressively when I get bored, but 80% of the time its 2500rpm or less.

[fenixus]

Originally Posted by pmesfun

Yeah, I've been starting to drive aggressively when I get bored, but 80% of the time its 2500rpm or less.

LOL, same here, I'd say even 99% of time I don't exceed 3k rpm (NJ traffic moves dynamically hehe).

now gas prices are getting jacked up again ... revolutions in countries having oil ...

[cf99]

Have any of you guys ever checked mileage of using premium vs regular? I've heard it can make a small difference, but enough of one that it compensates for the added cost of premium (tho I guess that depends whether your most common premium is 91 or higher cost 93). Never checked myself.

If premium stays at a fixed amount above regular (91 premium is generally 20 cents above 87 regular in my area) it becomes less painful to buy, percentage-wise, as overall prices rise. Yeah I know, that's a stretch

[fenixus]

Originally Posted by cf99

Have any of you guys ever checked mileage of using premium vs regular? I've heard it can make a small difference, but enough of one that it compensates for the added cost of premium (tho I guess that depends whether your most common premium is 91 or higher cost 93). Never checked myself.

If premium stays at a fixed amount above regular (91 premium is generally 20 cents above 87 regular in my area) it becomes less painful to buy, percentage-wise, as overall prices rise. Yeah I know, that's a stretch

I believe the 1mz-fe (or any V6 for that matter) gets better MPG, if driven under same conditions, with premium fuel over the regular one.
another thing is that not everybody likes limited performance of 1mz-fe on regular fuel.

5s-fe (or any 4cylinder with 9.5:1 compression ratio) will rather only feel sportier (and not always) with better fuel, but you won't see any MPG improvement, so bottom line it's not worth it for those.
another thing is that 5s-fe engines are made to run best with regular 87 octane fuel and if actually yours is running much better with premium then it would be common to say your engine is out of tune as 87 should make it run at most optimal specs and MPG.

[Jason.MZW20]

Originally Posted by fenixus

I believe the 1mz-fe (or any V6 for that matter) gets better MPG, if driven under same conditions, with premium fuel over the regular one.
another thing is that not everybody likes limited performance of 1mz-fe on regular fuel.

Yeah, the 1MZ advances the ignition timing a bit more with 91 or higher. It makes the combustion efficiency rise. Anytime the ignition timing is retarded, efficiency of the engine falls as the fuel is ignited later in the cycle, which can waste gas. Knock corrections definitely cause poor efficiency since the timing is retarded to the "safe zone" point. Can be 5* BTDC or lower. I've seen as low as -12* BTDC.

The 5SFE has stunted ignition timing maps, so 87 is the best fuel regardless - unless you're experiencing knock.

[projektvertx]

Originally Posted by fenixus

I believe the 1mz-fe (or any V6 for that matter) gets better MPG, if driven under same conditions, with premium fuel over the regular one.
another thing is that not everybody likes limited performance of 1mz-fe on regular fuel.

I can confirm both points actually. MPG improvements, yes. Power, realistically, the number has been contested a lot. But there is a difference. This is the first gen 1MZ.

pmsfun, your car should be premium only. My mom has a 98 Avy, and the owner's manual calls for premium only (91 octane or greater). And I'm pretty sure I remember it being written on the fuel door too.