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Using lower than recommended gas....does it matter if you're on a long or short trip?

A

Accipiter22

Banned
A friend of mine is trying to tell me that it's ok to use lower than recommended grade gas in his Maxima if he's only using it for driving around town since it's stop & go anyway....I say pre-ignition doesn't depend on your speed....who's right?
 
Originally posted by: Accipiter22
A friend of mine is trying to tell me that it's ok to use lower than recommended grade gas in his Maxima if he's only using it for driving around town since it's stop & go anyway....I say pre-ignition doesn't depend on your speed....who's right?
Click to expand...

u
 
My personal experience is that ping happens during acceleration, so I would think if anything, you would be better off using the crappy gas at highway speed where you aren't digging into the throttle. Of course, if your ECU will retard ignition to compensate, so that there isn't actually any pinging going on, it really doesn't matter anyway.
 
Neither of you.

Pre-ignition depends on engine load and temperature mainly. Additionally, modern cars with knock sensors can often (not always) retard timing enough that using regular fuel will not cause detonation even when premium is recommended by the manual. However, retarding timing decreases an engine's efficiency and power output. It's possible to lose 10% to 20% of an engine's power when running on regular (if the engine is supposed to run on premium) due to the effects of having the engine management retarding spark timing.

ZV
 
Originally posted by: Zenmervolt
Neither of you.

Pre-ignition depends on engine load and temperature mainly. Additionally, modern cars with knock sensors can often (not always) retard timing enough that using regular fuel will not cause detonation even when premium is recommended by the manual. However, retarding timing decreases an engine's efficiency and power output. It's possible to lose 10% to 20% of an engine's power when running on regular (if the engine is supposed to run on premium) due to the effects of having the engine management retarding spark timing.

ZV
Click to expand...

I was under the impression that, despite the power loss, lower grade fuel in a car did no actual damage. Is that correct?
 
Originally posted by: BlinderBomber
Originally posted by: Zenmervolt
Neither of you.
Pre-ignition depends on engine load and temperature mainly. Additionally, modern cars with knock sensors can often (not always) retard timing enough that using regular fuel will not cause detonation even when premium is recommended by the manual. However, retarding timing decreases an engine's efficiency and power output. It's possible to lose 10% to 20% of an engine's power when running on regular (if the engine is supposed to run on premium) due to the effects of having the engine management retarding spark timing.
ZV
Click to expand...
I was under the impression that, despite the power loss, lower grade fuel in a car did no actual damage. Is that correct?
Click to expand...
As long as there is not pre-ignition (i.e. the ECU is retardning timing to prevent ping), then that is correct. If you hear pinging/knock/whatever you call it, you are causing premature wear on your crankshaft main bearings.
 
Originally posted by: BlinderBomber
Originally posted by: Zenmervolt
Neither of you.

Pre-ignition depends on engine load and temperature mainly. Additionally, modern cars with knock sensors can often (not always) retard timing enough that using regular fuel will not cause detonation even when premium is recommended by the manual. However, retarding timing decreases an engine's efficiency and power output. It's possible to lose 10% to 20% of an engine's power when running on regular (if the engine is supposed to run on premium) due to the effects of having the engine management retarding spark timing.

ZV
Click to expand...
I was under the impression that, despite the power loss, lower grade fuel in a car did no actual damage. Is that correct?
Click to expand...
That depends on whether the ECU can compensate enough. It is possible that there is not enough adjustment range in the ECU programming to fully compensate under certain conditions, in which case there will be both the power loss and damage to the engine from detonation.

ZV
 
(IMO) It's seems pretty stupid given that the cost is probably less than $2.00 per fill up between the two.

Tell your friend to give up a cup of Starbucks a week and use what the factory recommends.

The potential damage and efficiency loss will cost much more thanthan in the long haul.

FWIW

Scott
 
Most cars that "recommend" higher octane full can run on lower grades.

When it is cold I run Mid-Octane in the Corvette. But when the temps hit 80 I switch back to High. No noticeably lose of power or gas milage either.
 
You are correct, it doesen't matter. However, you're more likely to hear pre-ignition under high load conditions.

Use the recommended grade, folks.
 
Originally posted by: Eli
You are correct, it doesen't matter. However, you're more likely to hear pre-ignition under high load conditions.

Use the recommended grade, folks.
Click to expand...

Every car is different. I have had the Vette up to the red-line on mid-octane and no pings or knocks. Now I am not sure how well other knock sensors are for other makers. But Chevy seems to be a ok. 🙂

 
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