# Recommended Gas



## Lukasz (Oct 14, 2004)

Hey Everyone,
I was wondering what octane-rating gas everyone is using in their X-Trails... I was looking throught he manual, and it says that the recommended is 87 or 91 ... So far, I've just been pouring-in 87, and am pretty happy with performance. Has anyone had a chance to compare performance when used with higher octane fuel?


Thanks
Lukasz


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## Terranismo (Aug 31, 2004)

I use 95 octane out of necessity since I'm running advanced timing and no knock sensor.


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## manuelga (Dec 14, 2003)

91 octanes without any trouble at all.

Due to a State-Owned Petrol company, this is the higher octane gas we can get at Mexico.


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## Oreo (Nov 5, 2004)

I have used 87, 89, 91, and 93 octane and haven't seen much difference in performance, in terms of fuel efficiency. I monitor my fuel efficiency on a regular basis and have obtained as high as 29.8mpg, and normally run around 29mpg. These values don't seem to be affected by the octane rating, although I haven't statistically analyzed the data.

Greg



Lukasz said:


> Hey Everyone,
> I was wondering what octane-rating gas everyone is using in their X-Trails... I was looking throught he manual, and it says that the recommended is 87 or 91 ... So far, I've just been pouring-in 87, and am pretty happy with performance. Has anyone had a chance to compare performance when used with higher octane fuel?
> 
> 
> ...


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## Lukasz (Oct 14, 2004)

Oreo said:


> I have used 87, 89, 91, and 93 octane and haven't seen much difference in performance, in terms of fuel efficiency. I monitor my fuel efficiency on a regular basis and have obtained as high as 29.8mpg, and normally run around 29mpg. These values don't seem to be affected by the octane rating, although I haven't statistically analyzed the data.
> 
> Greg


I guess I'm not missing on much by not fueling up with the higher octane. 
On a different but possibly related topic, there is a ticking when the engine is idle, and sort of a whistling/moaning when accelerating and in gear, and I was wondering if either are normal. The moaning/whistling, is only when the accelerator is depressed (even slightly) and the noise seems to be directly related to the engine RPMs. 
This is the first 4-banger I've ever really driven, and i tend to be over-sensitive in general.
Thanks
Lukasz


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## Terranismo (Aug 31, 2004)

Tell your dealer to check out your precat on the exhaust manifold, it may be breaking up.


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## AlexP (Feb 24, 2005)

Lukasz, my engine seems happy to run on 87 octane (regular gas) even under load. You'll get better gas mileage running on lower octane gas if there's no pre-ignition happening, and the gas is less expensive too. From the description of the sound you're hearing, your engine isn't knocking. I wonder if you might be hearing the alternator whining?


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## Lukasz (Oct 14, 2004)

AlexP said:


> Lukasz, my engine seems happy to run on 87 octane (regular gas) even under load. You'll get better gas mileage running on lower octane gas if there's no pre-ignition happening, and the gas is less expensive too. From the description of the sound you're hearing, your engine isn't knocking. I wonder if you might be hearing the alternator whining?


You're right, it probably is the alternator. I've been hearing it since new, I guess I'm just over-sensitive. 
And Terranismo, thanks, I will look into the precat. But wouldn't that be more of a rattling noise if it were the precat? (BTW, the car is not even 1 year old yet. It has about 12000km on it...)


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## Terranismo (Aug 31, 2004)

Not really, you'll hear a pinging and popping noise from the engine when it is cooling down (after driving and when it is off). this is due to the precat material inside expanding and contracting in the exhaust manifold. QR25DE engines (in the X-Trails) are prone to precat blow outs, with recalls already in place for Australia and service being done on Sentra B-15 SE-Rs which share the same engine. My truck is almost 2 years old with only 15,000K on the clock and the first thing I did was gut by precat from the manifold. In fact it was done by the dealer :thumbup:


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## Lukasz (Oct 14, 2004)

Terranismo said:


> Not really, you'll hear a pinging and popping noise from the engine when it is cooling down (after driving and when it is off). this is due to the precat material inside expanding and contracting in the exhaust manifold. QR25DE engines (in the X-Trails) are prone to precat blow outs, with recalls already in place for Australia and service being done on Sentra B-15 SE-Rs which share the same engine. My truck is almost 2 years old with only 15,000K on the clock and the first thing I did was gut by precat from the manifold. In fact it was done by the dealer :thumbup:


Yes, I realize that when the engine is turned off, the pinging sounds are from the engine cooling down, but this is very distinguished, a noise. It's not exactly pinging, but more like the sounds of an extremely muted-down tractor. (hehe)

Thanks again for the replies,
Lukasz


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## aussietrail (Sep 24, 2004)

*91-95 Octane*

Hi Guys,

I've posted this in another thread, but I was using the 91 octane normal unleaded fuel for a while now and decided to change to 95 octance *Premium* unleaded fuel and noticed a slight improvement in milage.

While my fuel consumption was about 10-10.5lt/100km's using the lower grade unleaded fuel (91 octane) since I started using the higher grade fuel with 95-98 Octane, my fuel consumption improved to 9.6-9.9lt/100km's.

The higher grade premium unleaded costs about 7c/litre more than the normal unleaded, but am making that difference up with achieving higher milage.

So, I think paying extra for a better quality fuel is worth it in the long run and it's better for engine as well.

Nissan does recommend you run your exy on premium unleaded if you can afford it.


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## ValBoo (May 19, 2003)

*87 octane*

Funny ???,

I just checked my user manuel and it says to use 87 octane minimum (not 91). strange...

(But I think there is two types of mesured units for Octane level.... Perhaps someone could clarify this for us.)


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## wolwol (Apr 3, 2005)

on my manual, it needs at least 91 octane


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## Avery Slickride (Jan 6, 2005)

The 2.5-litre in Canada is detuned to 165 HP, which probably means lower compression, which means the Canadian standard regular gas, at 87 octane, is all we need. Different motors in different markets might need something else.
I have never heard of premium gas improving mileage or performance. If your engine doesn't knock, ping or run on, you don't need it.


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## Zac (Mar 10, 2004)

Guys. You also have the QR engine. You can use 87, but using premium has benefits including less retarding of timing and better mileage. Overall, it is better for even the QRs tuned to 165 BHP. If you have modded your car, you absolutely must use higher octane.


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## AlexP (Feb 24, 2005)

Here are a couple of links that dicuss octane rating and engine peformance, and quotes from them...


http://www.superchargersonline.com/content.asp?id=105

High octane fuel does not burn cleaner, it does not clean your engine, it does not increase horsepower or torque (unless you are experiencing knock), it does not smell better, it does not increase fuel economy (unless you are experiencing knock) and is not better for the environment. If you buy higher octane fuels for any of the above reasons, STOP!


http://www.shell.ca/code/motoring/encyclopedia/gasolines/octane.html

The value that relates most closely to actual driving conditions is the average of these two values: Road Octane Number = (RON + MON)/2. This Road Octane value is the one referred to in Shell stations: Shell Bronze gasoline has an octane rating of 87, Shell Silver is 89 and Shell Optimax Gold is 91.

Occasionally, less scrupulous Canadian gasoline outlets will use the confusion of these different octane measurements to exaggerate their octane rating claims, by advertising their fuel's Research Octane Number - which will be higher than the Road Octane Number. It is also a common practice in many European countries to advertise the Research Octane Number on their pumps, so you may see unexpectedly high octane values when travelling abroad. In Canada, motorists should always be sure that the octane number a vendor advertises is its Road Octane value, not its RON.

Engines in vehicles built for sale in North America are designed to a specified octane requirement to make sure they don't knock or ping (engine knocking reduces the amount of power it can deliver to turn the wheels). Once that octane level has been met, in normal instances your car will not experience more power or better mileage if you use a higher octane fuel.


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## ValBoo (May 19, 2003)

Thanks for the links Alex;
that was good reading.


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## Lukasz (Oct 14, 2004)

AlexP said:


> Occasionally, less scrupulous Canadian gasoline outlets will use the confusion of these different octane measurements to exaggerate their octane rating claims, by advertising their fuel's Research Octane Number - which will be higher than the Road Octane Number. It is also a common practice in many European countries to advertise the Research Octane Number on their pumps, so you may see unexpectedly high octane values when travelling abroad. In Canada, motorists should always be sure that the octane number a vendor advertises is its Road Octane value, not its RON.


So is the Road Octane Value the same as the AKI index? I was trying to find that out, and actually this is what led me to confusion, as the manual states two different rating types. As quoted directly from the manual: "Use unleaded regular gasoline with an octane rating of at least 87 AKI (Anti-Knock Index) number (Research octane number 91)"

So as I'm understanding from what you said that AKI is the actual number on the pumps, and the octane rating we normally go by?

Lukasz


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## AlexP (Feb 24, 2005)

Lukasz said:


> So is the Road Octane Value the same as the AKI index? I was trying to find that out, and actually this is what led me to confusion, as the manual states two different rating types. As quoted directly from the manual: "Use unleaded regular gasoline with an octane rating of at least 87 AKI (Anti-Knock Index) number (Research octane number 91)"
> 
> So as I'm understanding from what you said that AKI is the actual number on the pumps, and the octane rating we normally go by?
> 
> Lukasz


The terminology is confusing. Here's another quote from a bike site...

The pump octane is also referred to as the Anti-Knock Index (AKI). AKI is determined based on an average of the Research Octane Number (RON) and the Motor Octane Number (MON). The formula is RON+MON/2 normally abbreviated as R+M/2 on the pump. 
The MON is a measure of the gasoline's ability to resist knock under sever operating conditions. MON affects high speed, part throttle and performance (under load such as in passing). The RON on the other hand, is a measure of gasoline's ability to resist knock under less sever conditions. RON affects low to medium speed knock and engine run-on (dieseling). For a given AKI, RON is typically 8-10 points higher than the MON. As an example, 87 AKI (pump octane) fuel would have a MON of 82 and a RON of 92.


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