rmesola

iTrader: (2)

try looking in the web a little more, i read an article from consumers report a year ago about this issue and the conclusion is there is no benefit to higher octane gas for motors designed for regular fuel...

for imports (mostly european) and some Japanese, high end motors designed for higher octane will benefit from the difference due to inherent designs/ecu mapping. Also, there was mention about sulfur content in regular fuel that is lesser in premium fuel. This sulfur content does not affect regular engines, only high performance motors, and sulfur deposits could ruin your sensors and cause the CEL to go off earlier. May also clog your injectors and other parts. Know anybody who puts 87 in their BMW?

If the Nissan tech checks your engine and notes excessive sulfur buildup inside the engine, guess what, they void your warranty for using the wrong fuel....

lowrider

iTrader: (3)

Actually, you're wrong -

Below is a copy and past from the 2006 Infiniti Owner's Manual:

FUEL RECOMMENDATION

Sedan Automatic transmission models
Use unleaded regular gasoline with an octane
rating of at least 87 AKI (Anti-Knock
Index) number (Research octane number 91).

For improved vehicle performance,
INFINITI recommends the use of unleaded
premium gasoline with an octane rating of
at least 91 AKI number (Research octane
number 96).

Sedan Manual transmission and
Coupe models

Use unleaded premium gasoline with an
octane rating of at least 91 AKI (Anti-Knock
Index) number (Research octane number 96).

If premium gasoline is not available, unleaded
regular gasoline with an octane rating
of 87 AKI number (Research octane
number 91) may be temporarily used, but
only under the following precautions:

O Have the fuel tank filled only partially
with unleaded regular gasoline, and fill
up with unleaded premium gasoline as
soon as possible.

O Avoid full throttle driving and abrupt acceleration.
However, for maximum vehicle performance,
the use of unleaded premium gasoline
is recommended.


It's all mapped in the ECU.

Lou

Chineseguy

iTrader: (7)

If you didnt want to but better petrol in your car then you shouldnt have bought the car. simple as that

Kolia

iTrader: (2)

Nah, I didn’t do it myself

Different mapping is used to change to feel of an engine. The torque curve can be adjusted according to suit the intended buyer, how it goes up in revs and so on. People often think their car’s potential is maxed out from the factory. It’s not.

Cars that run on premium fuel are harder to sell. Every manufacturer would rather make cars that run on regular. Unfortunately, you run the risk of having less HP than the competition because they would run on premium.

Now, a 350Z is marketed as a sport car with a history of racing. Its buyer is a somewhat hardcore guy who will accept some compromises for the sake of performance. Running on premium is ok for this guy. Engine mapping is optimized.

A G35 buyer on the other hand is more inclined to get a luxury sedan with a sporty zest. He doesn’t want a no-compromise sport car and is not interested in a toy that needs exotic fuels. Running on regular fuel is a plus for his car. Engine mapping is de-tuned to accept the lesser octane rating, using the same component than the Z (cheaper).

These cars both use the same engine. All the Nissan models except the Sentra has a VQ35 available. With some different states of tune, to suit the intended character of the car, one engine platform is used (cheaper).

Those peoples who think that regular and premium fuel are identical are mistaken. Obviously, they have never done any real testing of fuel. At school (many years ago), we had a MON engine to measure the octane rating of fuel and also a clear cylinder engine. Playing with different compression ratio, ignition timing and so on, it was obvious not all fuel are created equals!

As far as knowing if the Z can run “fine” on regular fuel, it obviously won’t explode if you do. Nissan knows some stupid people won’t read their manual or think there is a vast conspiracy to make people buy premium fuel. Nissan doesn’t want to have its engine blow up. It cost warranty money, it also give a bad reputation to the marque. Who here is not proud of its “Bullet Proof VQ35?”. So Nissan makes sure the engine will protect itself and last long enough if run on regular fuel. What is “long enough”? Hard to say. One thing is for sure, it’s not good for the engine on the long term. A knock sensor react to knocking. Meaning that it has happened a couple times before the timing and injection is adjusted…

Running regular fuel might not even bring any savings per miles driven! Highway miles are the worst for that. The engine then runs in closed loop, listening to the knock sensor and advancing the ignition to the max for fuel economy. The more advance, the more power you get from each ignition. At a constant load (cruising at 75 mph) that means less fuel is necessary the more advance you get… Regular fuel will detonate before premium, limiting how much advance the ECU can give. This can lead to a much better fuel economy with premium fuel, some times enough to make each miles driven cheaper.

dnguyent

iTrader: (5)

You missed the point, that's why it seemed so simple.

dnguyent

iTrader: (5)

Lou, thanks for clarifying this. My coworker got the '06 Auto w/280hp engine, and told me his users manual stated use of regular unleaded. I then checked the specs online, and that's where I saw: regular unleaded fuel for the other models of the G35 lineage. All we needed was someone w/a G35 to verify this, and you've done so.

Kolia: insightful post...as always.

I believe the case is closed (in my book).

-Don