So my parents are convinced they dont need premium

[mamiyarz67]

please please help me tell them that running plus in their 3.0 h6 in the tribeca that has a whoopping 2000 miles on it.
*sigh* i tried to tell my dad that the freeking computer will only handle So much knock and even then why bother, i know gas is mad expensive but an extra 10C a gallon wont kill them..
anyone got a coupla good reasons other than knock/detonation
he wont listen to me on that point - i need a "i put gas in and car exploded" story
i hate when they think they know more than subaru

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[Ruff]

The h6 doesn't need premium does it? Just use what the freakin car asks for.

[FalconRS]

I also was under the impression the H6 didn't require premium. Either way, should say on the inside of the gas flap. Just look, if it says regular unleaded recommended, no need to spend more money.

[FalconRS]

I stand corrected, recommended fuel according to subaru is Premium 91.

[Ruff]

Originally Posted by FalconRS

I stand corrected, recommended fuel according to subaru is Premium 91.

Point that out to your parents mamiyarz67.

[El_Kameleon_G]

It's not required if you're not punching it everywhere. That's the only time better fuel works. Not when you are on part thottle. I think you can use a grade under the recommended for a while.

[Kevin Thomas]

Tell your parents that they should use the fuel that the owners manual recommends. If they do not and the dealership find that there is fault with the car based on using the wrong grade of fuel, that their warranty will be voided.

You may have some people argue this point over on here but remember this. If you drove a Porsche 911 Turbo and you put 87 octane in it when the owners manual clearly states to use (insert higher/premium grade gas here), would Porsche as a company be responsible for engine damage or the owner of the Porsche?

[rs2.5-3.0]

took the words right outta my mouth

[Hayes]

30,000 dollar car. Manufacture say minimum 91 octane. I think I would NOT use anything less and take a chance except for a real emergency like death or dismemberment and running the patient to the hospital. Why is an extra 2-4 dollars a week more importaint than the 5-6,000 dollar engine? JMHO eddie

[mamiyarz67]

yeah thats what i dont get
they did this with their Audi A6 3.0L before (required plus, ran it on reg in the winter.. apparently because they dont need higher octane in the winter..)
which i said, no, with colder temps, more dense air = needs better octane, not lower!
yeah that could be a point that if they have problems and see the fuel itll be warr. void

[Jesse00]

just tell them if they continue using cheaper gas than required, they would need to get a new car soon. A blown engine from using incorrect gas wont be covered by warranty...

[poormansporsche]

You should also point out that the low octane to high octane is getting cheaper. Whats the big deal now days? High octane is still 20 cents higher than regular and the price has tripled. Just say "You'll pay 45 dollars to fill up but 47 is too much?" I can almost see this being a bit different if gas was still cheap. Like 13 dollars vs 15 dollars. But you're already paying 45 or so 2 more bucks isn't going to break the bank.

Also! If your ride says 91 use 91. My old GTI would idle horribly if i used 89. Detonation kills engines. I say there is never a good reason to use less than what the manufacturer recommends. Even if you baby the throttle.

cheers

garrett

[Patrick Olsen]

Well, I'll be the dissenter and say that a modern ECU is more than capable of compensating for using 89 or even 87 in an engine that's designed for 91. Will the performance be optimized? Obviously not. Is there any chance that the engine will be damaged or they could "blow the engine" by using lower octance gas? No.

Originally Posted by mamiyarz67

ran it on reg in the winter.. apparently because they dont need higher octane in the winter..)
which i said, no, with colder temps, more dense air = needs better octane, not lower!

Actually, that's not true. Engines are under much higher stress when temperatures are higher - the cooling system has a harder time removing heat from the engine, the air charge temperature is higher putting you that much closer to a knock/detonation threshold, etc.

From a Gasoline FAQ website - "You can often reduce the octane of the fuel you use in winter because the temperature decrease and possible humidity changes may significantly reduce the octane requirement of the engine."

"Back in the day", when cars were still carbureted and didn't have fancy electronics to run the engine, knock was way more likely to occur in the summertime, not the wintertime.

The density of the air coming in doesn't have anything to do with the octane requirement. There's a reason the engine has an ACT sensor - that's one of the inputs the ECU is going to use to determine air density and hence determine how much fuel to inject. If the engine is using a MAF (vice MAP), it's directly measuring the amount of air coming in. Either way, the denser air is mixed with more fuel to obtain the correct AFR, and the octane of the fuel has nothing to do with that.

Pat Olsen
'97 Legacy 2.5GT sedan

[rs2.5-3.0]

As a rule of thumb, ALWAYS FOLLOW THE OWNER'S MANUAL!

mamiyarz67: I am not going to sound like a know-it-all, although I have the education/ experience to comment. So I will leave you with the following link which will more than answer your question.

I strongly suggest that you have you parents read it. Or print it and let them read it:

http://auto.howstuffworks.com/question90.htm

Good luck,

Brian