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Discussion Starter #1
Hi guys,

Just something to talk about.... :eek:

I have an automatic 4wd '04 RAV S and I never used regular gas on my RAV and always give my baby PLUS (I guess the second most expensive to PREMIUM gas).... :p

Since cost of fuel nowadays is sky rocketing, I am wondering if using REGULAR have any effect on the mileage and the lifetime of the engine.... :shock: ....of course considering the climate and the driving style.....surely this will have an effect on my pocket :lol: but will changing the fuel type does something good? :?:


I leave these questions to the experienced and to the experts.......
:roll:
 

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The Rav4 was designed to use regular gas so it will be fine.
 
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Jeff said:
The RAV4 was designed to use regular gas so it will be fine.
I agree.

I used high OCTANE on my Toyotas till about 1994 when all my research forced me to switch to 87 because I found no evidence of better performance...


Although, I must mention that my 1988 Accord with 292k miles on it did not knock when run on 93 octane... Whenever I did the mistake of putting 87 octane in it, the engine knocked like crazy....
Got used to better food?????!!!!!!!!!!!!

I have never got an answer for that.
 

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Using higher octane gas in a car tuned for 87 can actually reduce performance and degrade your emissions systems faster.

It's not "regular", "plus", and "premium". That's marketing hoo-ha

It's just octane levels, if you're using a high compression and/or turboed car(and a few other cases) you need 93. Otherwise 87 is what you need. You're not settling for anything.
 
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The Australian RAV2002 manual syas its tuned for 91 octane which is exactly what unleaded fuel is in Aussie, and that is what I use.

Brian
 

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when your 4.2s get a little bit more older you will notice a difference when using premium fuel. my 96 4.1 normally runs on normal unleaded (91 ron) but every few fills i use premium (98 ron) and u can feel the difference
 

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If an older car appears to become dependent on premium fuel you probably need a Sea Foam(or similiar brand) engine treatment.

Though I don't know why a dirtier engine would require something less prone to detonation. Would almost think it should be the other way around.
 

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The standard explanation for that is that older engines sometimes develop carbon buildup that effectively raises the compression ratio, making them more susceptible to knock. You either start running mid-grade or premium fuel or you decarbonise the combustion chamber.
 

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my rav doesnt ping with normal unleaded. i use premium every few fills to keep the injectors clean (as premium contains detergents) and to get extra mileage out of a tank.
 

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bmorton said:
The standard explanation for that is that older engines sometimes develop carbon buildup that effectively raises the compression ratio, making them more susceptible to knock. You either start running mid-grade or premium fuel or you decarbonise the combustion chamber.
Ah yeah, guess that makes sense. Carbon build up = smaller chamber = higher compression

In the US anyway all levels of fuel have the same detergents due to EPA regulations.
 

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Discussion Starter #11
wow what a simple change in gas type brings out a lot of issues.....

anyways, i will be switching from time to time form regular to premium....just like mohit said.

since i have 4wd my average miles for a full tank of REGULAR gas (12 gallons) is 275 miles i get like 22-23 MPG not bad for a city and highway combo driving.....

thanks guys, another knowledge in my info bank............this site is the best
 
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I am a chemist with some experience with engines and fuels. If an engine (such as the RAV4 engine) is made to work on regular gasoline, it is normally a complete waste of money to use a higher octane gasoline. One possible exception is when driving at high altitudes up steep grades in the mountains. If the engine starts pinging when driving up steep grades, a higher octane gasoline can sometimes help (although a good conditioner would work better - see below).

Many years ago, higher octane gasolines had more cleaning detergents, but in recent years (at least in the USA) low and high octane gasoline have the same amount of detergents.

ALso be aware that there are many ways to measure octane. Many countries have different systems for determining octane. A fule with a rating of 87 in the USA may have a totally different rating in another area. The octane rating system in the USA is actually an average of two common ratings.

Perhaps the best way to improve fuel performance and keep the inside of the engine clean is to use a high quality Gasoline Conditioner. An once of a true conditioner in each tank of gas can: (1) keep the fuel fresh even when the car is not used for long periods; (2) eliminate water in the gasoline; (3) keep the entire fuel system clean; (4) eliminate carbonization in the cylinders; (4) keep the injectors clean; and (5) make the fuel burn more efficiently. After burning one tank of conditined fuel, you will feel the difference.

If you do add anything to your fuel, make sure that it is a true conditioner rather than an additive (which can actually hurt an engine). Many engine professionals use fuel conditioners with the brand name Hammerdown (check out this on Google) for gasoline qand diesel enginer. These conditioners are made by LV Petro, PO BOx 388, Alford, FL 32420. (850) 579-2111. The specific conditioner that would work for the RAV4 gasoline engine would be DFT #2000 G. These conditioners are sometimes hard to find in auto stores but can be ordered from the manufacturer.
 
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I use ethanol based fuel here(in canada its available at a few places). My toyota manual says its safe to use.

Ethanol reduces emissions and cleans the injectors to boot. I have not noticed any performance reduction or mileage(some say its gives less power). I use octane 87.
 

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I guess I'm in the minority........I almost always use premium as I figure it cleans the combustion chambers and injectors continually.......as opposed to adding a conditioner now and again. Started doing this in the 25 yrs I had H2O VW's and had them all to high mileage.
As they say "Pay me now or pay me later......"
 

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Bluenoser said:
I guess I'm in the minority........I almost always use premium as I figure it cleans the combustion chambers and injectors continually.......as opposed to adding a conditioner now and again. Started doing this in the 25 yrs I had H2O VW's and had them all to high mileage.
As they say "Pay me now or pay me later......"
The regular up there doesn't have detergents?

Using premium is actually worse for the car if it's not tuned for it. It actually causes buildups.
 
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I think you will have to repeat yourself....

nouse4aname said:
Bluenoser said:
I guess I'm in the minority........I almost always use premium as I figure it cleans the combustion chambers and injectors continually.......as opposed to adding a conditioner now and again. Started doing this in the 25 yrs I had H2O VW's and had them all to high mileage.
As they say "Pay me now or pay me later......"
The regular up there doesn't have detergents?

Using premium is actually worse for the car if it's not tuned for it. It actually causes buildups.
.....at least another 50 times. It's amazing how stubborn some people are even when stuff is explained!!!..... and will continue their mantra of "I use premium because my engine runs better", with no SCIENTIFIC basis or understanding!!! ....Just because it's more expensive does not mean it's better :roll:

I totally agree with your assessment, and will go one step further to shed some additional light on the issue.
FIRST:
All gasolines are NOT created equal!!!! ....and so all of them do not have the same levels of detergents. Yes, they do have the EPA mandated minimum level of detergents, but this is nowhere near adequate to keep modern engines with very tight tolerances running at their optimum. CHEVRON gas is the best in this regard and was THE FIRST company to have all 3 grades of their gas contain the same HIGH level of detergent (called TECHRON). A few other gas companies have now joined this list. SHELL started out with only their 91 Octane (or "premium") gas having the best detergents (callled "V-power"), but now they've supposedly implemented it in all three grades. A full list of quality brands that qualify as having the best and highest levels of detergents can be found at the following website:

www.toptiergas.com

....and for the last and final time: 91 Octane (or Premium) does not make your engine run better if the engine is designed to run on 87 octane!! :roll: ...and it can actually make your engine run worse as was mentioned above. (Notwithstanding the EXCEPTIONS as stated above by some posters, which are right on the mark, such as with old engines that have carbon buildup in the cylinders etc. - but even then, the correct remedy would be to "decarbonise" the cylinders rather than just go the "higher octane route" because the engine ECU will have to alter other variables....and the engine components are not designed to operate at this higher "effective" compression ratio) ......but as was stated in a post above, the BEST remedy is prevention: Use one of the above mentioned "high quality" gasolines or at least use a fuel conditioner once in a while to keep the engine "clean". Since 1998, I have only used CHEVRON gas in all my vehicles, and if CHEVRON is not available in a certain area, I try to stick to one of the gasolines in the above mentioned top tier list.
 
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As a former fuels chemist I have to disagree with some of the last posts on fuel octane and detergents. Using a higher octane gasoline will not in any way make your RAV4 (or any other car engine designed for 87 octane) run any better or worse. I rregularly read the fuel chemisty scientific publications for fuel chemistry and I am not aware of any published, peer-reviewed, scientific evidence available anywhere to dispute this fact (only opinions and BS). If anyone out there has other published, peer-reviewed, scientific information to the contrary (other than just opinions or BS), please provide full details to this forum. Using higher than 87 octance gas rating (USA combined rating) for your RAV4 results in only one change to your RAV4 operations - it is more expensive with no benefits. If you want to waste your money, thats fine - the oil companies will love you. All the major brands of gas sold in the USA have about the same level and type of detergents (even most of the off brands, as they are normally purchased wholesale from the major brands). The only way to slightly improve your fuel efficiency and engine performance, is to use a top-level fuel conditioner; and then only if you use your RAV4 in harsh conditions (see my last post).
 

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Firstly, does the 2AZ-FE and 1AZ-FE have a knock sensor? If so, it should be able to adjust the timing to the higher octane fuel.

I've sort of noticed running it back on normal unleaded that it lacks a bit of torque compared to the middle of the range fuels.
 

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SmellyTofu said:
Firstly, does the 2AZ-FE and 1AZ-FE have a knock sensor? If so, it should be able to adjust the timing to the higher octane fuel.

I've sort of noticed running it back on normal unleaded that it lacks a bit of torque compared to the middle of the range fuels.
The knock sensor tells the computer to retard the timing if knock is detected. It doesn't keep advancing the timing until it encounters knock to take advantage of anything more than 87.
 

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Are you sure of that? I have not read anywhere that it is or isn't the case.

In fact I am looking for the SAE technical papers on the 2AZFE but there's only the ZZ series engines online. This will show a lot of technical info on the engine itself (I'm surprised there's not more since the 2AZFE is found in the Camry).
 
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