OT: Gas Grades & Requirements

[flere-imsaho]

I figure someone around here knows the answer to these questions:

If an automobile "requires" premium gas, does it really "require" it? If you use 87 or 89 octane gas, are you hurting it?

If an automobile "recommends" premium gas "for better performance" (my father-in-law's older Maxima says this) can you get by with 87 or 89 octane? If you do so (again), are you hurting it?

Thanks in advance.

[sachmo71]

hope this helps

[Mustang]

If it requires a 93 octane, I would suggest using 93. Lower octane numbers will cause performance issues and knocking in the engine which could damage it.

What car of yours requires 93?

[moriarty]

Originally Posted by flere-imsaho

I figure someone around here knows the answer to these questions:

If an automobile "requires" premium gas, does it really "require" it? If you use 87 or 89 octane gas, are you hurting it?

If an automobile "recommends" premium gas "for better performance" (my father-in-law's older Maxima says this) can you get by with 87 or 89 octane? If you do so (again), are you hurting it?

Thanks in advance.

No, it doesn't really "require" the higher gas octane. But I would recommend it.

The biggest problem with running lower octane as others have mentioned is the potential knocking problems you could have at high speeds or more likely climbing hills. Most newer cars though have technology that adjusts for this so you likely won't cause 'knocking' damage to your engine.

However, you are almost always better off going with the higher octane if required in your owners manual. The reason is that your engine is designed to run optimally at that octane level. Yes the electronics may correct for it if you run say 87 octane, but you'll get incomplete combustion and as a result worse fuel economy. So even though you're saving $$ by paying less $ per gallon, you'll end up buying more gallons and the net effect is you'll lose $.

Of course, to convince yourself you can always run a test. Compute your mileage for your standard commute with 93 octane (if recommended) and then recalculate it with 87 octane (or 89). I'd fill it up several times with each to get a good sample set. You should see your miles per gallon ratio decrease with the 87, and some simple math would tell you whether you are paying more or less with the 87.

The other thing to think about is if you have incomplete combustion in your engine it could lead to build up of carbons and other crap in your engine. So if you're leasing or planning on keeping your car a short time you may not care, but if you're planning on getting 10 years of life out of your engine beware the lower Octane where not recommended. Edit - some gasoline additive cleaners like Techrolene (sp?) from Chevron may help a bit with this.

[Young Drachma]

Yeah, my mother's Nissan Maxima requires it and if she doesn't, it does that knocking sound. So, she stopped doing the lower octane thing years ago. Needless to say, in today's gas prices...she's paying a pretty penny. But oh well.

[flere-imsaho]

Thanks for the info, folks. That helps a lot.

This isn't for a car we currently have, but we're looking at buying a 2nd car (to replace my beloved 1993 Mazda 626 which died a couple of months ago). We're looking at a specific segment (wagons - for puppydog) and we'd prefer not to pay the higher gas price if it isn't necessary. Knowing we'll want to stay with Regular is helpful in that it cuts some of the choices down.

[moriarty]

Originally Posted by flere-imsaho

Thanks for the info, folks. That helps a lot.

This isn't for a car we currently have, but we're looking at buying a 2nd car (to replace my beloved 1993 Mazda 626 which died a couple of months ago). We're looking at a specific segment (wagons - for puppydog) and we'd prefer not to pay the higher gas price if it isn't necessary. Knowing we'll want to stay with Regular is helpful in that it cuts some of the choices down.

I'd add gas mileage as a factor in your search.

For example if you drive say 15,000 miles per year and premium is $2.90 per gallon and regular $2.70 per gallon. If the car requiring premium gets 25 miles per gallon, and the one requiring regular gets 22 miles per gallon you'll end up spending less per year with the car running premium ($1,740 vs. the one running regular $1,841).

[RPI-Fan]

Originally Posted by Dark Cloud

Yeah, my mother's Nissan Maxima requires it and if she doesn't, it does that knocking sound. So, she stopped doing the lower octane thing years ago. Needless to say, in today's gas prices...she's paying a pretty penny. But oh well.

She actually pays LESS now compared to a few years ago.

While 87 octane gas prices have risen on the order of 50%, the other ones remain the same 10-20 cents higher than 87, that they were years ago.

[stevew]

Originally Posted by RPI-Fan

She actually pays LESS now compared to a few years ago.

While 87 octane gas prices have risen on the order of 50%, the other ones remain the same 10-20 cents higher than 87, that they were years ago.

Yeah, sadly 93 octane is actually a "deal" in today's market.