Effect of premium gas

Since purchasing my 99 Camry SIX cylinder in 1999, I have used regular unleaded gas, per the manual. The manual mentions how I could get "improved performance" using Premium gas. I stand to be corrected but, here in Canada, I believe the usual 3 grades of gas available are rated 87, 89 and 91 on some kind of octane scale. Last week, when the tank was close to empty, I refilled with Premium gas. This week, when THAT tank was almost empty, I again refilled with Premium gas. So far, I haven't noticed any improvement in performance, i.e. it ran great before, it still runs great.

QUESTION: How many consecutive tankfuls of a different grade of gas does it take before the computer in the 99 Camry "retrains" to the different octane level?

Reply to
Sharx35
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The performance it refers to may be in MPG, not in power or speed. It is not unusual for a car to get a little better gas mileage with higher grade fuels, but it's never a significant amount of difference either. Also when performance "power"-wise is increased there's more to the equation................generally upgrade to consumer level fuels will have almost no increase in power.

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MUADIB®

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Reply to
MUADIB®

The ECU does not recognize the octane number, instead, it listens to "knock" (detonation) and varies the timing and fuel accordingly. Octane is detonation retardant. Higher octane prevent detonation. But higher octane will cause engine difficult to start, especiall in cold weather. Basic rule is to put the smallest number of octane that you will not notice any difference or hear pinging (noise of detonation) Unless you have a high performance engine, turbocharged or supercharged engine that is tuned for higher octane gas, you will not notice any different between regular or premium gas. I have both 3sgte and 1MZFE and I only put regular in the Solara.

Reply to
ST185

You will get a horsepower increase with a higher octane fuel, and also better gas mileage. However, the improvements in both of these might not be very noticeable. Both improvements would be more noticeable if you are driving your car for longer distances (and engine was fully heated up) and the ambient temperature is fairly high 90F +. Since you are in Canada, you might try midgrade in summer and regular in winter.

Reply to
Mark A

I get about a 15% increase in MPG with premium in ALL my Toyotas, and none of them knock, either...

Reply to
HachiRoku

Hi,

got a 96 V6 Australian Bulit Camry, always use Shell Optimax (about 98 I think).

Takes about 2 tanks to clean it out and run on the high octane. I notice a small improvement in power (noticeable but not wheel spinning etc), engine runs smoother and better mpg.

Was dubious on the mpg side but I visit my relatives in Nowra a bit and alwas wondered why my fuel economy on the return trip (600 miles) was always worse than the trip there. Much the same conditions there and back (in terms of slope etc).

Figured out, eventually, that the Service Station in Nowra sold Premium Unleaded and not Shell Optimax. Found one that had Optimax and the fuel economy came back. Got about an extra 50 miles out of the tank. But thats on a long straight, relatively flat run with dual highway.

Get about 30mpg around town but there's a bit of freeway in that as well and usually keep the revs under 3000.

rgds

Peter

Reply to
Peter

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