I was wondering if anyone can answer a question for me ? Firstly I dont pretend to know alot about cars so bare with me if my question is stupid . My owners manual for my Tiida says to run it on unleaded petrol ( 91 octane) will I be better off running it on premium unleaded ( 95 or 98 oct) ? will this be better for the running of the car ? or would i just be wasting my money on the extra cost of the petrol?

Modern engines are able to adjust timing to match whatever octane you are using. You can safely run regular unleaded (which I guess is 91 where you are?) without harming the engine. The engine will be able to make more power with Premium, though, so you're not wasting money if you run premium.

Ok thanks for that .

ok i actually know alot about this topic. When your car recommends regular unleaded, its better to use that than use premium unleaded. Most entry level cars fuel injectors are unable to support premium fuel, however the benifit of premium is that you get more kick out of your engine. Nissan's are actually notoriously known for their clogged fuel injectors from owners who have used dirty or non-recommended premium fuels. Upper class cars like audio, bmw mercedez recommend premium because theyre engines are made with high quality parts that are able to withstand the increased power. For the versa, use the recommended regular unleaded and do not use premium or your injectors will clog.

Ok I have search the manual a few times. Most vehicles list a sea level octane and a 5000+ft octane. I can only find it saying 87. At sea level, that is fine, but up here 85 is our regular unleaded, 87 is midgrade & harder to find & 91 is premium.

Has anyone found the use 85 octane at elevations above 5000 ft statement?

XterraVersa wrote:Ok I have search the manual a few times. Most vehicles list a sea level octane and a 5000+ft octane. I can only find it saying 87. At sea level, that is fine, but up here 85 is our regular unleaded, 87 is midgrade & harder to find & 91 is premium.

Has anyone found the use 85 octane at elevations above 5000 ft statement?

Not on the Versa. However, I owned a '97 Saturn SC1 coupe that was rated similarly, I ran it on regular (87) down here at sea level, but when I went on vacation to Eastern Idaho/Yellowstone, I ran 85 octane and didn't hear any knocking or pinging.

wow. here in CA we have 87, 89, and 91.87 is good enough. expensive too.gas in CA for unleaded regular (87) is $3.10-$3.24.i wish g.w.bush would die and rot in hell for being such a dumbass.i hope he gets his pen15 shot of by someone.

penpen-commander wrote:i wish g.w.bush would die and rot in hell for being such a dumbass.i hope he gets his pen15 shot of by someone.

That is the dumbest thing I have heard. How is it the presidents fault? What is your solution to the problem? No matter who was president, we would have gone to war in Iraq regardless of what the Democrats say. It may have been under the UN flag, but the USA would still be there leading the charge.

The high prices now are that the law of supply & demand no longer works with oil. It is the oil speculators that should be blamed. Oil is 2x what it should be based on current supply levels. They are just "worried" oil supply will be disrupted. 4 years have passed, has the oil supply been interupted yet? NO!!!

The other problem is that there are so many blends of gas. Bush is pushing the EPA to standardize the blends to keep costs down. This is slowly happening by regionalizing the formulas. This has aided by reducing the price of ga by ~$0.10/gallon.

Mandotory ethonal is also driving the price of gas up by because of the costs and lower effiency. If 10 % ethonal reduces mileage by greater than 10%, which it does in my cars, are we really saving gas? No!!

i know we would have went to war regardless if it was bush or gore or kerry.i was in that war with iraq.

i'm just saying:i hope bush dies and that his pen15 gets shot off.

i know why gas is up.i also know gas prices could've dropped anytime, but it didn't.

Let's not let yet another gas thread become a pointless political shooting match.

XterraVersa wrote:Mandotory ethonal is also driving the price of gas up by because of the costs and lower effiency. If 10 % ethonal reduces mileage by greater than 10%, which it does in my cars, are we really saving gas? No!!

Not to mention the fact that ethanol isn't exactly the best thing for fuel injectors.

Ok, I thought that the higher the octane the higher the flash point of the gasoline is. So, if you have 85 octane and 91 octane it takes a hotter spark to ignite the 91 octane compared to 85 octane. Higher end engines that generate more horsepower and run at higher temperatures need a higher octane because the heat from the cylinder walls can get so hot that it will ignite the gas before the spark plug does. So basically you have 2 explosions, one from the gas and the cylinder walls and the other from the gas and the spark plug. These two explosions collide and cause detonation or knocking/pinging. Detonation is bad because it can wash the oil away and cause premature engine wear.

Again , this is what I thought the differences in octane were.

Yes, detonation is why some engines need higher octane: octane is (to put it one way) a measurement of a fuel's detonation-resistance. So higher performance engines, especially high-compression engines, tend to need higher octane fuels to avoid "detonation" or early ignition, which can be harmful to the engine. But modern engines can retard timing to combat detonation; the problem is that retarding timing also decreases power output. High-comp engines (usually only older ones) are sometimes prone to "dieseling" after they're turned off when using low-octane fuels.

ok, sorry.

the dealer where i bought my versa told me that higher octane gas will also give me less miles per gallon in mine with the cvt. i don't see how octane can decrease gas milage, but that is what he said.

versawildman wrote:the dealer where i bought my versa told me that higher octane gas will also give me less miles per gallon in mine with the cvt. i don't see how octane can decrease gas milage, but that is what he said.

I'm not sure how it works, but I can verify that's true. Each of my last 3 cars have all had worse fuel mileage from premium than low-grade.

Im with pen-pen on the bushs pen15. Oh yeah the fuel. I have put 87 in my car since day one. no problems!

Not for nothin', but before talking about the Iraq War and its effect on oil prices, folks here should check out how much oil we get from Canada. That said, what's the excuse for high fuel prices? Canada's a virtual goldmine of natural resources! Just my two cents...

versawildman wrote:the dealer where i bought my versa told me that higher octane gas will also give me less miles per gallon in mine with the cvt. i don't see how octane can decrease gas milage, but that is what he said.

octane 91 exsists because there are engines that need it for their higher comnpression built engines. What that means is the fuel can widithstand more compression before it explodes. Since in an engine you want the spark to ignite the explosion and not the gas itself. For regular engines like mine and the Versa (octane 87) putting 91 octane does not improve its performance/mileage. The Versa is programmed to compressed the gas to a certain ratio tuned for octane 87 before igniting the spark, higher octane helps the engine to compress the gas some more but the engine is not tuned to do that in the first place!

So the gas companies like to call high octane gas "cleaner" but in truth it has been more "refined" to suit higher compression engines. Don't buy the BS! Use the gas that was designed for your car!

As for E10 (Octane 90) that's a whole new ballpark of discussion...

philmcneal wrote:
So the gas companies like to call high octane gas "cleaner" but in truth it has been more "refined" to suit higher compression engines. Don't buy the BS! Use the gas that was designed for your car!

And as for "cleaning", don't forget to use gum-out or similar injector cleaner every now and then. After 20k or so miles without it, your car may lose up to 2 mpg just from inefficient spray.

philmcneal wrote:So the gas companies like to call high octane gas "cleaner" but in truth it has been more "refined" to suit higher compression engines.

Not True... 87(85 in Denver) is extracted lower in the distiling stack. 91+ is extracted higher up. No further refining needed. 91+ is more expensive because there is less of it in a barrel of oil. 89(87 in Denver) is a blend of the two.

E10 is a great example of playing politics. It hurts gas mileage greater than 10%, but is promoted to save gas.