I just purchased a used Infiniti G35 Sedan 2003 with Automatic transmission. It has 1/4 a tank left of regular (lowest octane) gas. Should I refuel with regular or use midlevel or highest octane? If I should use the highest, should I wait until it's almost empty or mix it in now?
Thanks.

 

It's okay to mix it up. I've always used the premium (higher octane) fuel and always will.

 

The 03's can take 87-93, but I always go premium. It does make a difference. I've done some tests with a friend, and I pull noticeably faster on 93.

 

damn i wish we had 93 in san francisco. iv never even seen 93. that must feel nice on the engine. but the prices!! i made the mistake of filling up with 89 and boy did i regret. it felt so bad. but gas in frisco is so expensive. i saw 450 today for 91.

 

haha its like 4.71 for 91 in fresno

 

no ****, thats crazy.

 

yuuuppp gas is a biiiiiiiiiiitttccchhhh

 

Makes me wanna take the bus.

 

4.29 for 93 here in fort lauderdale

 

Back when I lived in the UK we had 90, 95 and 97(@BP stations) 98(At another brand gas station) premium octane. We also have 99 & 102 Octane in several selected Tesco gas stations. We had a huge choice but then again it cost $$$$

Where I am currently I only have 2 choices, 90 or 95 (I always go for 95) plus petrol here is **** CHEAP!!!

 

Those octane levels aren't directly comparable. What is displayed on US pumps is R+M/2, the higher of these 2 are what is displayed in Europe.

 

i keep it at 91 usually, and 94 when it's cheap, but quit complaining about 4 something a gallon, 94 is getting close to 6$ a gallon (us$, us gallon, don't wanna know how much it is for our gallons).
had budgeted about 65$/week for gas, now closer to 80-90$/week.

 

3.99 a gallon in jersey for 93 octane

 

its okay to mix. Premium will give you better performance and possibly better mileage.

$4.45 for 93 in NW chicago suburbs, the other night was the first time i had ever pumped over $75. I had to do two transactions to get a full tank becuase of the stupid fraud prevention that cuts off the pump at $75.

 

Just when I think that, maybe, I get better mileage with 91 I have an experience like my last road trip (80% highway) where I got just under 20mpg.

Maybe they are finally starting to use ethanol here, which may knock off up to 1mpg. New state law says stations are supposed to identify if they use it.