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Discussion Starter #1
Hello to all! This question has probably been asked a million times before.

The RAV4 uses 87 Octane regular unleaded fuel. We all know that.

(Stepping on soapbox)

When I bought my RAV4 in June, my salesperson recommended me to use premium unleaded (92 Octane or up) with my RAV4 because the aluminum block engines in the new Toyotas need it.

Does this claim have any truth to it? Is there any benefit at all for using a higher octane fuel for a car that doesn't need it, particularly the RAV4? From what I know, using fuel with a higher-than-necessary octane rating actually increases pollution because the engine spews out more unburned fuel. I am not a chemist or mechanical engineer to explain it completely. :p

If the need for a higher octane rating is FALSE, then why would car manufacturers "recommend" us to use something we don't need - and could do more harm than good?

Is there a deal between the oil companies and auto manufacturers to "coerce" drivers into spending more money on (unnecessary) fuel for their "new, flashy" cars (that don't really need it), at the expense of our environment and our wallets?

Personally, I think that the only benefit of using a higher rating of octane is not so much the octane part, but that many oil companies claim to put more "cleaning" additives into their highest octane fuel.

I know that if you drive certain models of luxury or sports cars, such as Lexus, premium leaded is REQUIRED, due to the compression ratio.

(Stepping off soapbox.)

Thanks for your explanation. :)
 

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No need to use anything more than 87. As you said using a higher octane results in more unburnt fuel. Which will only waste gas and wear out your emissions equipment faster.

Salesmen are salesmen. They don't necessarily know what they're talking about and shouldn't be given much credibility.
 

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All of the documentation from Toyota I have read says to use 87 octane with the Rav4.

The whole idea of higher octane is to reduce pre-ignition, that is, the self-igniting of the fuel before the piston reaches full compression and the spark plug ignites. An engine with a higher compression ratio needs higher octane gas to reduce the amount of pre-ignition. That is why most cars that require premium gas tend to be high-performance cars with higher compression ratios.

Here is a simple explanation of octane:
http://www.howstuffworks.com/question90.htm

The Rav doesn't need anything better than 87 octane unless you notice a lot of pinging or knocking. The idea that using premium gas may improve power or fuel economy on a car designed for regular gas is just a coincidence, which depends on the individual car.
 

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I've been using 87 octane for 300,000 miles in a RAV4 and it seems to be holding up fine. 271,000 on my '98 with 87%. The extra cost to me would cost me a lot more each month. It would cost me another $25.60 a month. or $307.20 a year.
 
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Discussion Starter #6
Thanks for all of your responses.

Looking back, I still remember the service department of a local Toyota dealer telling me to use the highest possible octane for my old 1995 Tercel. I knew that they were full of crap when the told me that.

I guess it's a big conspiracy: If we use higher octane fuel, a) The oil companies (partners with the manufacturers) make more money, and b) the dealers make more money when we bring back our cars with failing emissions systems, thanks to unnecessary use of higher octane fuel. :p

I'll continue to use my good ol' 87 octane. :)
 

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It's not a conspiracy, it's just that there is a common misconception (even among some mechanics) that premium gas is better for your engine.
 
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Discussion Starter #9
Mohit said:
It can be better for your engine (ie. better cleaning agents).
That's the only rationale that I can think of so far.

However, buying fuel additives (STP fuel injector cleaner, etc.) for each fill-up is still cheaper than the extra cost for premium unleaded.
 

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I don't know about gas in Australia, but gas here in the states has the same additives and detergents whether it is 87 octane or 93 octane. The idea that premium gas is somehow "cleaner" is a myth that petroleum companies want you to believe so you spend more money on the premium stuff. The only difference is the octane rating and the price.

I should have mentioned this earlier, but premium gas can actually be worse for your engine if it was not designed to run on premium gas. Premium gas will not be able to fully combust properly in an engine with normal compression, which can cause carbon buildup and foul the spark plugs. As time progresses your engine will become more reliant on the high octane gas to combat the effect of the carbon buildup. That is why some people who have always used premium say their vehicle doesn't run well on regular gas.

Some people claim to notice a slight performance boost when they switch to premium gas, and while this may be true, it does not last long. The ECU eventually adjust to the higher octane gas and performance returns to normal.

While premium gas may help a higher mileage engine by reducing ping and knock, it is useless for a newer engine that was designed for regular gas. Modern engines have knock sensors (as does the Rav) which can compensate for knock. If you have bad knocking or pinging with a newer engine that was designed to run on 87, then there is a problem with the engine and not the grade of gas.

By the way, don't use fuel additives with each tank fill, because the gas already has them, so you're just wasting money. You can use an FI cleaner every 15-30K miles but any more is a really a waste. Besides, if you find that you need to use that stuff often, then there is a problem with the engine.
 

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Maybe you guys don't feel a difference going from 87 to 93 (i take it that 87 is regular unleaded and 93 is premium unleaded?) because we get better fuel here? Our regular is 92 to 93, premium is 95 to 96 and super premium is 98. All i can say is that you would have to drive on 98 fuel to see and feel the difference we do in Australia...perfect excuse to come down here for a holiday :wink:
 

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California's just a funny place that tops out at 91. Can get 93 in most other states.

It's just measured differently overseas. We use (RON + MON)/2. Australia just uses the outright RON measurement. From a brief glance on the net it looks like the minimum requirement in Australia is a RON of 91 and a MON of 81. So that would be a US octane of 86, though it would be labeled 91 over there.

Any difference you're feeling is likely a placebo effect. Engine's simply not tuned to take advantage of it. Unless the Australian RAV is tuned differently?
 

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Mohit's Rav is also 9 years old, so it may appreciate premium gas more than our newer Ravs.
 

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With regional differences, i guess the engines must be slightly different? or maybe emission levels in countrys vary enough that variations in octane are less important, as the manual recommends 95 octane or higher. All you can buy is premium here, which i assume is that grade. it mentions 'use of fuel with an octane lower will cause persistant heavy knocking. If severe, this will lead to engine damage'. There is Optimax, but it sounds like it doesnt really need it.
 

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Yeh maybe i can tell the diff between 91 and 98 coz my RAV is so old and it appreciates better fuel but it's too expensive to buy all the time. I use it every 4 or 5 fill ups to keeps the injectors clean and to get a little bit more mileage every 4 or 5 weeks :)
 

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ser02rav4 said:
personally Ive noticed that in Europe Toyota recommends to use Premium, not 87 as atated in the manual, so I use 92 instead of 87.
Which, again, is because it's measured differently overseas. Not because they're calling for a more knock resistant grade.
 
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Discussion Starter #20
Modern engine management systems will adjust the ignition timing to extract the best from whichever grade of petrol is put into it, some measure the acceleration of the crank after each spark, some have "Knock " sensors and will adjust the timing if the fuel is ignited too early and Knocks.

Years ago when we had distributers and mechanical adjustment for ignition timing the grade of fuel was more important, stick with what suits you best

I also understand that the US is reducing the sulphur content of its diesel to below European standards soon, which would result in a cleaner burning diesel, add to this that Toyota will soon be launching a new high output 180 bhp (I think) Diesel engine, which would give plenty of power, stacks of torque, and good fuel economy, I would be interested to see if Toyota follow VW by launching Diesels in the US
 
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