My daughter's QX50 with the VC turbo engine gets pre-ignition on regular and medium grade gas, but it's fine on premium. I've had a few cars over the years where premium is recommended, but they have always run regular with no problems. My understanding of what happens is the spark advance is somewhat reduced if the knock sensor "hears" any knocking. And this happens before a human driver can hear it. I told her to ask the dealer about it at her next oil change, but I'm wondering if this engine is somehow different than other high-compression engines that run just fine on regular gas.
Premium fuel required in 2021 Infiniti QX50
- Thread starter mbres2000
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Those "other" engines don't really run fine on regular; they just run. Premium fuel has the advantages of better additives and slightly better gas mileage and horsepower.
I'm guessing most 3rd owners of those Infinitis will use 87 octane. Will it matter?
Probably not. Do you think any rental cars get premium?
Required and recommended are 2 very different things.
Owners manual for that vehicle states at least 91 AKI. 87 can be used temporarily but ONLY if you partially fill the tank with 87 then fill up the rest of the way with 91+ ASAP. You also have to avoid full throttle and abrupt starts.
Owners manual for that vehicle states at least 91 AKI. 87 can be used temporarily but ONLY if you partially fill the tank with 87 then fill up the rest of the way with 91+ ASAP. You also have to avoid full throttle and abrupt starts.
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Shhhhh, cheap US consumers don't want to be offended, and definitely don't read owner's manuals.
It is good to see a few automakers recommending premium fuel, especially with turbos.
FUEL RECOMMENDATION
Use unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-KnockIndex) number (Research octane number 96).
If unleaded premium gasoline is not available, unleaded regular gasoline with an octane rating of at least 87 AKI number (Research octane number 91) may be temporarily used, but only under the following precautions:
Have the fuel tank filled only partially with unleaded regular gasoline, and fill up with unleaded premium gasoline as soon as possible.
Avoid full throttle driving and abrupt acceleration.
Use unleaded premium gasoline for maximum vehicle performance.
FWIW - Many turbos have lower CR than their non turbo counterparts. CR alone may not be the determining factor.
Rental cars do not get anything other than 87 unless a customer fills it with something else.
There is a big difference between "recommended and required" Very few cars "require" premium, but they have more power when higher octane is used. Recommended does not mean mandatory.
When a 91-93 octane engine is run on 87 octane, in addition to retarding the spark timing, the fuel injection may be enriched. Result, poorer gas mileage, less power, less efficiency.
Whats the effective compression ratio with boost?
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