My family's G37 is barely 2000km. My mom took out the car today and put in regular gas (87 octane). I could tell immediately because the car wasn't accelerating well as it used to.

My question is how important is premium gas to the car and why?
The salesman had told us that it's ok to use 87 octane for every 3 premium fillups but I don't know anymore after seeing the performance dwindle this way. I would like to know why premium fuel is important and what would happen if I continue to use 87 octane. Thanks

 

your salesman is 100% wrong.
read your gas tank,it says "premium fuel is recommended."
we have high compression motors,that is how the high hp is acheaved. I'm surprised you don't have any knocking from the ecu.
there are more reasons than not to use premium fuel in the g.

 

For the engine to perform the way it was designed you need premium. Higher octane means your engine can perform at its proper compression ratio. Using 87 won't damage your engine as it can compensate (knock sensors can help with timing when using lower octane gasoline), but you might see worse mileage and reduced performance.

Car salesmen are mostly just salesmen. To them it wouldn't matter if they were selling women's shoes or cars. Basically, they don't know jack.

Tell Your mom that saving $.25 per gallon only comes out to about $150/ yr at 12000 miles a year. Considering you could be losing gas mileage, and the car is worth about $40k, is that really worth it. But it is your mom's car so she can do with it as she wishes.

 

i was told 89 is okay on the highway by the salesman...but honestly the price difference between 93 and 89 or even 93 and 87 doesn't even make that big of a difference in the grand scheme of things...or doesn't seem to be worth the potential risk of damage

 

Octane rating is the fuels ability to reduce engine knock.

Higher octane allows manufacturers to increase compression, and overall increase engine efficiency.

By putting low octane gas you are risking engine knock if the engine was designed for high octane.

Could also be risking pre-detonation. (detonation of the A/F mixture before intake valve closes) I always believed low octane fuel had a lower flash point. If someone believe I am wrong, please correct me.

 

You're driving a $40k car, and want to put the cheapest gas in it. Premium fuel is what this motor and ecu are designed to run on.

 

87 burns faster which leads you to fill up more often and you'll also hear those knocking sounds...

 

I put 87 when I was leasing my previous two G35. No problem whatsover.

 

FUEL RECOMMENDATION
VQ37VHR engine

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:

●

●

However, for maximum vehicle performance, the
use of unleaded premium gasoline is recommended.

CAUTION

●

and may also affect warranty coverage.

 

The real question is how many more threads do we have to have on this topic when it’s been discussed at least 100 times before?

 

Use premium.

[/close thread]

 

i was the same way when i first bought my ride but then someone said it is almost equal to giving up one starbucks run. and ever since, i never looked back

and i drastically reduced my starbucks intake/expense!

 

My mechanic friend told me regular gas is MUCH MORE EXPENSIVE than premium gas. It's your wallet, your choice.

 

my G is a lease but i don't really want to reduce the power of the car and yes you do feel that the pick is worse and you get less gas mileage

 

I think it actually says "required".