Using regular 87 octane on a turbo engine

[2strokeNorthstar]

We've always run premium in our Juke Nismo. Turbo direct injection. 201k miles and counting. Not 1 problem with the motor, yet..... I'm not confident it would still be going if we ran 87 its whole life. 91 is recommend "for optimum performance" in the manual

 

[Rand]

I would run 91 in it.. or move on.
Plenty of other turbos run fine on 87 but maybe not this one.
The owners manual:

 

[oil_burner]

Exactly. If you want to use 87, then buy a car that only requires 87. I'm not seeing the economics in paying more for a turbocharged engine, then trying to save a few bucks by burning low octane fuel in it.

Unless the owners manual specifies that it's OK to burn 87, I would stick with 91. If something got damaged by low octane fuel, the dealer is going to know it, and most likely it won't be covered under warranty.

And if it's out of warranty, that's even worse. Because you'll be paying for it. And it's a sure bet it will end up costing a lot more than what you saved by burning the cheap gas that caused it.

in response to this and the numerous other "why buy an audi" comments:

the only reason I am buying an audi is because we have awful pothole and frost heaved roads here. No other car manufacturer, and I mean none, does as good of a job for sound damping the suspension impact noises. I have tried them all, and I'm extremely sensitive to low frequency NVH from suspension and tire impacts.

I really don't care about the turbo, the DTC transmission, the power, etc. My only criteria for is a compact crossover that has excellent sound damping. I am literally obsessed with a quiet car and have ripped apart several car interiors to line the doors and floors with dynamat and MLV sound damping. NOTHING is as quiet as the Audi, and I have zero love for the brand, I would rather own japanese any day. We currently drive a lexus IS sedan which started off nice and tight, and in 4 years of driving the roads have destroyed that car to where the dashboard has multiple rattles and squeaks, several struts have blown, even the ride height sensors have snapped in half from the rough pavement, and I'm running 16" tires with a taller sidewall than stock. I don't want to drive a full on body on frame SUV, but it seems like our roads require it.

 

[Nessism1]

Modern engines have knock sensors, which pull back the timing as needed to avoid engine damage. As long as you are using fuel that meets the minimum standard, damage should not be a problem.

As far as optimal performance is concerned, some people report better mpg and power using high octane fuel. So bottom line: if you want to get maximum performance, use premium fuel. This doesn't mean that using "regular" is bad, though.

With my Civic turbo, I use 87. I rarely push the rpm to high levels, although I do drive aggressively. Yes, I'm cheap, but I've driven enough miles using 91 to know that the cost vs benefit is not worth it. Unless you push redline regularly, even with a premium car like an Audi, why spend extra? Just because of the name? I think not.

 

[tcp71]

Because it's not fuel that's pre-igniting. It's a fuel/oil mix. It matters little if the fuel is 87 or 93 octane when the octane of the oil is ~25. This is why reducing more reactive elements from the oil (calcium and sodium, in particular) reduces the risk of LSPI. It's also why increasing ZDDP and MoDTC, which act as anti-oxidants resisting the breaking of bonds (combustion), reduces the risk of LSPI.

Thanks. Makes sense if oil is bypassing the rings or valve seals. Or PCV, I suppose.

 

[wemay]

No difference whatsoever in my Malibu 1.5T. But it calls for 87 or higher. If my vehicle called for higher, I'd use that exclusively.

We also traded in a Santa Fe Sport 2.0T that called for (and we used) 87 octane, running great with 248k miles. No issues.

 

[Glenda W.]

in response to this and the numerous other "why buy an audi" comments:

the only reason I am buying an audi is because we have awful pothole and frost heaved roads here. No other car manufacturer, and I mean none, does as good of a job for sound damping the suspension impact noises. I have tried them all, and I'm extremely sensitive to low frequency NVH from suspension and tire impacts.

I really don't care about the turbo, the DTC transmission, the power, etc. My only criteria for is a compact crossover that has excellent sound damping. I am literally obsessed with a quiet car and have ripped apart several car interiors to line the doors and floors with dynamat and MLV sound damping. NOTHING is as quiet as the Audi, and I have zero love for the brand, I would rather own japanese any day. We currently drive a lexus IS sedan which started off nice and tight, and in 4 years of driving the roads have destroyed that car to where the dashboard has multiple rattles and squeaks, several struts have blown, even the ride height sensors have snapped in half from the rough pavement, and I'm running 16" tires with a taller sidewall than stock. I don't want to drive a full on body on frame SUV, but it seems like our roads require it.

I completely understand sound sensitivity.

You ever hear a money counting machine?

That’s what my bank account sounded like fixing that darn VW engine as the bills flew out….

 

[edyvw]

I completely understand sound sensitivity.

You ever hear a money counting machine?

That’s what my bank account sounded like fixing that darn VW engine as the bills flew out….

I had three of those engine, still have one, and I spent far less than I did on the Toyota Sienna (actually, combined BMW and VW, I spent less than on Sienna).

 

[RDY4WAR]

Thanks. Makes sense if oil is bypassing the rings or valve seals. Or PCV, I suppose.

Oil is always bypassing the rings to some degree. It's held in the valleys of the cylinder wall. With port injection, you have sufficient fuel wash to mitigate this issue where as you don't with direct injection. In the early days of GDI, the method for dealing with this was to run the engine rich, particularly spraying additional fuel during that range of crank rotation where LSPI occurs. Thus, fuel dilution in the oil was a problem and fuel efficiency wasn't as good as it could be. It's also what lead to so many valve deposits. Much of this has been resolved with changes to the oil.

 

[Japanese]

after owning one - BiL had to go cheap on everything else

I see them every day at the drive through at McDonald's/Burger King.
It's sad.

 

[odie]

91+ with more detergents . Top Tier fuels such as SHELL , EXXON , MOBIL , SUNOCO , etc.. Go to https://www.toptiergas.com/gasoline for all brands .

Also may want to see this about detergents , https://bobistheoilguy.com/forums/threads/list-benefits-of-91-93-octane.400374/page-2#post-7386585 . Scroll down page for video .

 

[Oillover]

I don't want to drive a full on body on frame SUV, but it seems like our roads require it.

Seems like you found your answer.
GM makes several naturally aspirated vehicles which don't require/recommend premium that would suit your needs. Considering your climate, if I were in your position, that's where I'd put my money.

Besides, considering how the Lexus was beat to shreds from your roads, who's to say the Audi won't suffer the same fate in a couple of years?

 

[IndyIan]

I wonder what happens if you restrict the intake significantly? Or create a significant boost leak? If the turbo can only make 50-75% of the expected boost, the effective compression ratio must be a lot lower, and then you don't need 91 octane?
I guess an 87 octane ECU tune would be the simplest option, I assume these cars have electronic waste gates, so if its programmed to leave it open more, then it never sees high boost at any rpms.

 

[tvaughn]

My business partner, a non-car person, who leases Q5's every 3 years and just does maintenance by the book, adamantly runs 91- though from the cheapest gas station possible.

Her lease ends in December. This particular Q5 has about 25k miles but has already had the alternator replaced- start/stop wasn't working, sort of a blessing in disguise, and the car had shuddering issues with its transfer case, which changing the fluid seemed to resolve so far. Apple CarPlay likes to randomly shut off at times as well. Frankly, I am not that impressed with the car.

 

[Rand]

Unless you push redline regularly, even with a premium car like an Audi, why spend extra? Just because of the name? I think not.

did you happen to read the owners manual excerpt? this isn't a honda or subaru turbo engine.
I'd say following the owners manual is a reason for "why spend extra"

 

[Nessism1]

did you happen to read the owners manual excerpt? this isn't a honda or subaru turbo engine.
I'd say following the owners manual is a reason for "why spend extra"

Going off what was posted in this thread, which states 87 minimum, 91 recommended, that means that 87 is okay to use. Are you suggesting this information is wrong? And if so, why?

 

[Japanese]

Owners manual calls for 87 min but 91 recommended.

Can you, please, post a picture of the manual where it says that?
I don't see a reason to don't run 87, if it was mentioned by the manufacturer.

I'm asking that because online it looks like the Q5 requires premium gasoline of 91 octane or higher.

 

[Patman]

I don't understand why this is a question. Follow the owners manual. The only difference is that your engine will not make max power on 87. I have no idea what that means in actual HP/TQ.

Weather has zero bearing on fuel choice.

Ambient temperature has a big impact on the octane needs of an engine actually. If an engine needs 91 octane on an 80 degree day in order to avoid timing being pulled out, it can get away with 89 octane and maybe even lower when it’s below freezing outside. Colder air equals less chance of an engine detonating under acceleration.

 

[Andyd95]

I’ve seen 3 1.8T EA888 Jettas for CEL with misfire and knock above threshold faults this summer where the customer runs 87. Instruct them to run 93 and re-check. They always return to say thank you and that took care of it, no parts needed.

 

[tbm5690]

My EA888 Gen 3 noticeably retards timing in the summer even on 91 when getting on it. I guess if you're never going to punch it you won't have to worry about losing power on 87.