Hello I have a 2017 g37 sedan...

I took it to the dealer due to a knocking noise in the engine. They said it was because I was putting 87octane gas and I needed an EFI cleaning asap to remove all the gunk build up.

So my question is....

Is it really because I used 87octane a couple of times why I'm getting a knocking / rattling noise?

Will the EFI cleaning really help? Since they want like $250.00...???

And the engine kind of hesitates and bogs out when going up hills?

Thanks

The need for a cleaning is absolute BS. Unless you've put nothing but garbage gas (off brand, really cheap stuff) in it. Try a tank or two of premium and see if it makes a difference.

Your engine has a higher compression ratio therefore you will need to use premium gasoline 93 octane (recommend shell gas) the octane rating of the gas means how easily the gas ignites and burns as well as how clean of the burn due to higher compression ratio of your cylinders using 87 octane gas means the fuel will ignite too soon causing predetenation (knock) very serious problem there. As far as cleaning goes I would clean out the fuel lines by putting in techron in the gas tank but wouldn't go as far as cleaning the throttle body can pick that up for about 10$ At Walmart

I have a 2008 G37S. Bought it new.
I have almost always put 87 in it, and never had any knocking.

Lower octane rating means the fuel/air mixture will burn faster and hotter and can ignite sooner due to a cylinder hot-spot (pre-ignition). The usual problem is detonation which is caused when the mixture is ignited normally by the spark plug but because the mixture is burning and expanding faster than expected (by design/tuning), the flame front strikes the piston as it is still rising towards TDC. This causes ALOT of extra stress on engine components such as pistons, connecting rods, crank, etc.

Check your owners manual. If it says to only run 91/93 octane, run it. If it says you can run 87 octane but 91/93 is preferred, than you're fine with 87 octane.

I'd venture to say that all modern vehicles (since 2005 or so) have knock sensor, which will retard ignition timing if it detects detonation. It WILL decrease performance as compared to higher octane. It WILL NOT cause damage if your owners manual says 87 octane is okay.

Also, lower octane gas will NOT cause anything in your fuel or induction systems to get dirty (assuming you're not using old, contaminated gasoline). That dealer service department is looking for easy money.

FWIW

Using 87 Octane is perfectly fine in my opinion. I'm on my second Infiniti. My first 06 G35 was traded in at 171796 miles all on regular 87 Octane.

My engine does not knock!

Not even on a local hill while accelerating.



My current 2012 G37S with almost 70k miles has never seen a drop of anything other than 87 octane. I use WaWa gas locally in NJ and Pilot and Loves gasoline from truck stops while traveling.

Over almost twelve years and almost 250k miles, I've saved thousands of dollars by using regular 87 octane only.

A recent round trip from NJ to Florida produced excellent mileage results as have my previous round trips to
Florida



Local driving in Florida with frequent stops and short trips produces crappy MPG that most forum members complain about.
Over the road exclusively the G37 provides excellent MPG using regular 87 octane









The two best tankfuls were from Va to SC 249 miles and filled up with 9.448 gallons at Pilot for a 26.35 MPG
On the return trip the best tankful mileage was 26.23 MPG from Va to NJ. 301 miles and filled up with 11.374

Tires were inflated to 35lbs when cold. I also discovered that not using cruise control adds a couple of additional MPG's

Telcoman

Sounds like you really don't get up into the high RPMs so running the lower octane shouldn't cause issues, as you have witnessed. But push 5500+RPM and detonation occurs.....I feel sorry for your engine is your knock sensor or ECU delays retarding the timing.

I'd probably settle for 89 octane if I'm planning on running the tank 95% highway on a long journey but other than that, I'll keep it filled with Premium.

Why pay the Infiniti price if you settle for Toyota Corolla care?

ArmedAviator wrote:
Why pay the Infiniti price if you settle for Toyota Corolla care?

The Toyota Corolla is no comparison to the comfort and handling of the Infiniti

I usually shift between 3k and 3.5k RPM

I've never had a need to push my engine over 5500 RPM
Driving style has a substantial impact on both MPG and engine life.
Tons of threads on many complaining of poor MPG but they never detail their driving style that results in their poor MPG results.
The OP asked about the use of regular 87 octane.
I've never had a problem with its use but others might depending on how they push their engine into the high RPM range

Telcoman

And I am not disputing any of what you sad, telcoman. I just want the OP and others who read this to realize that they do put their engine in danger if they push it hard with 87 octane. One tank won't lead to an immediate issue, but repeated used of lower octane and driving it hard absolutely can result in a decreased engine life, as opposed to running premium gas. Worst case scenario is a catastrophic failure, but unlikely with knock sensors.

In the end, it's your car. It's your money. Buy 87 or 93 octane or anything in between. I will respect the manufacturer on this one. Sure it'll cost me a little more, but I also bought in Infiniti.....not a Corolla. I'm not pinching pennies. (That is what I was getting at with my previous post but appears to have been lost in translation)