Our gas is (MON+RON)/2. Euro gas is just RON; their 95 is roughly our 91 and their 98 is roughly our 93.

 

Very true because some days when it's nice and cool especially at night here in Miami my G just feels perfect and faster then days when it's hot and humid here and my G lags the performance that I wonder is it just me or the car lol. But agree that Z/G love cold weather .

 

Has no one here heard of heat soak?

 

Only time i notice my G driving differently is when the traction control kicks in and cuts some of the engine power to prevent me from looking like a fool in the ditch.

 

There's a reason why Infiniti recommends the use of premium. Higher octanes to prevent pinging and retarded (HAH! edit: retardation), correct? Why go between the different octanes? I've heard around that using a higher octane than recommended doesn't really do any good for cars in general, but then again...I have a friend who claims that higher octane gasoline in INFINITI/NISSANS actually do some good (shot at your 93 octane Sun gas)...maybe?

On a side note, you're probably getting that "lag" from heat soak. I've learned that without starting the car and letting it idle for a bit...the car isn't as peppy in the mornings...yes, yes I know the best way to warm up the car is via driving it; it idles rough (misfires) for a reason...blah blah blah...just my 2cents.

 

I've casually looked for 91 octane and have yet to find it here in NE Florida. So I'm stuck using the 93 octane (with higher price).

 

The cool weather has a huge effect on the G . There's an on ramp that I like to take advantage of on my daily commute to work, and on one particular morning when the engine was well warmed up but the temp outside was cool I was actually startled by how urgently the G accelerated. It was a truly significant difference.

 

Cooler, less humid air has higher oxygen density. Therefore more combustion per stroke. Humid air is less dense, and contains more water, which we know is not combustible. Even on two equally hot days, the day where the humidity is lower, the car will probably feel more repsonsive than it would be with high humidity in the air.

 

Question here, I have noticed that in the mornings or when the car hasn't run for a while (regardless of outside temp), it does run rough when first started up. After 15-30 seconds it smooths out. Is there a reason?

 

When I had my bike (suzuki 750) it ran Soooo much better when the day got cooler, around dusk. It was very obvious.

 

Could be richer while motor gets to temp?

 

When air is cooled, it become denser, allowing our engine to burn more fuel and produce more power. We can see the reverse affect driving up a mountain - the higher you get, the air becomes less dense and the engine produces less power. Of course, this is assuming humidity remains constant - as you said, when humidity increases, the air density decreases.

Regardless of density, the oxygen level is still 21%.

 

... I hit VDC every time i get in; Unless its raining...

 

G,

We need to have a talk . I'm no expert, but from what I can understand, the rough idle that you're talking about is the car's ULEV system (or whatever equivalent system we have - remember, I'm coming from a 2005 Acura TL). Anyways, the car misfires upon start up to help the car warm up (that's the rough idling for the few seconds that you're talking about).

By the way, I posted a reply in another thread about your RP comment. DON'T USE RP! It's not junk, but certainly not worth the extra $$$ you're spending for it.

 

thanks for your thoughts ... there are a lot of thoughts on RP that say just the opposite. When I'm due for the next oil change I plan on sending some off to Blackstone. Bottom line, I want to do what's best for the longevity of my car, we plan on keeping it a long time.