posted by
someone claiming to be Dave Berger
on
Fri Apr 13 02:19 CST 2001 [ RELATED]
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Just wondering what octane fuel most of the T-6 drivers use. I have been using 92 octane, does the T-6 engine run just as well on 89 octane? Thanks ...Dave
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posted by
someone claiming to be John
on
Mon Apr 23 03:52 CST 2001 [ RELATED]
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My mechanic said that in the winter, 87 is just fine, and in the summer it "seems to run more efficiently on the higher stuff."
The manual states that minimum 91 AKI (anti-knock index) is required, but from research at the Mobil gas website, it seems that when the pump gas says "87" it is the R+M number, which is different from AKI. I forget the actual number, but the AKI number for "87" pump gas (from Mobil anyway) is definitely greater than 91, like around 93 or 94 I think.
Regardless of the math and figures, I have noticed that my T-6 runs a little more powerfully on 89 or higher, especially in the summer time, and since I push it a lot, I will mostly use 89 this summer (I've been using 87). I notice that on 87 my turbos really kick in when I floor it, and then back off quickly, perhaps because of the pinging, but after a couple of tanks of super, it doesn't do it as much.
-John
'99 S80 T-6
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posted by
someone claiming to be Ian
on
Mon Apr 23 04:25 CST 2001 [ RELATED]
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Typically the manual will tell you to run low test (87 octane) and nothing else. I don't personally have an S80 but I've found that with most volvo's the best thing to do short of running high test all the time is to run low or mid grade most of the time and run a tank of high test (93 or higher) every 8 or nine tanks. This serves to clean out any gunk left by the lower octane fuels. If you can stick to mid grade all the time then go every 12 tanks or so and run high test. Running low all the time is the primary reason our cars fail emmission tests due to unburnt deposits on the valves, while running nothing but high test is ok but expensive.
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posted by
someone claiming to be Bart Bobbitt
on
Sun Apr 15 01:09 CST 2001 [ RELATED]
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I use mid-grade 87 AKI Phillips 66 or Texaco at home in northern Colorado for around town use. It gives about the same miles-per-dollar (mp$) numbers as premium 91 AKI gas. (I wish Chevron gas was available here, but alas, it ain't.) On the interstates, 91 AKI premium gas gives about 1 to 2 mp$ more than 87 AKI mid-grade.
The above is for fuel economy which I think should be based on some monetary unit; i.e., how far the car goes on a dollar's worth of gas. For fuel efficiency, then the traditional miles per gallon is the way to go. One has to decide what's better, fuel economy or fuel efficiency.
Volvo's T-engines are designed to perform best with premium gas and I'm sure they do. But unless one is driving at the extreme end of their performance spectrum, I don't think it makes any significant difference. Going down the interstate at 70+ mph is as close to extreme performance as most of us will ever do. According to Phillips 66, there's a bit more energy in a pound of premium than mid-grade.
And a can of BG 44K every 10,000 miles and a can of BG MI3000 every 3,333 miles keeps the fuel lines and combustion chambers very clean, too.
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posted by
someone claiming to be Charlie
on
Mon Apr 16 14:22 CST 2001 [ RELATED]
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The main reason for higher octane fuel is to retard the onset of detonation in high compression engines. In the old days (i.e. before feed back controls and computers), uncontrolled detonation created hot spots in the combustion chambers that if allowed to continue could literally burn holes in the top of pistons. Today’s engines have feedback controls that constantly monitor for detonation and when it detects the onset, it retards the spark and cuts back the boost in the case of supercharged engines. Both of these techniques serve to reduce combustion chamber temperatures, which is a good thing for engine durability in general. Today's engine controls will “learn” the parameters of operation and adjust to account for the current fuel octane level. If you assume the additive package is the same for all grades of fuel, an idea that I’ve heard from BP but have not confirmed, then lower octane fuel should not hurt the engine but at the same time will not provide top performance either….
On the other hand I follow the manual and always use premium fuel in my T6. Hey, it costs more so the additive package MUST be better right? It’s the American way to shop!;)
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posted by
someone claiming to be Jim Miller
on
Wed Apr 25 15:02 CST 2001 [ RELATED]
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Hi. Someone asked previously why my mechanic said that higher octane fuel was better for the turbos. His answer is somewhat supported by your post so I'm replying here.
He sad that the use of higher octane fuel will avoid "fuel flash and pre-ignition". He also said that there is less buildup of deposits around O2 sensors and catalytic converters so they should last longer and be trouble free.
He also said that it burns cleaner and is less damaging to the environment.
That' as good as I can relate!
Jim Miller
'99 S80 T6
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posted by
someone claiming to be Charles Linden
on
Thu Apr 26 04:22 CST 2001 [ RELATED]
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I don't believe that's quite right. All things being equal lower octane fuel burns more complete. Higher octane is more resistant to ping and lets you advance timing and compression, but is also harder to ignite. It seems strange but I have seen lit cigarette be dropped into 130 octane and not light. So usually you get more build up on the o2s and plugs with higher octane. As for fuel economy, you should get better mileage with low grade based on combustion efficiency, but the over all performance will suffer.
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posted by
someone claiming to be JackFlash
on
Wed Apr 25 16:57 CST 2001 [ RELATED]
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I've watched this topic with interest and more than a little amazement as people posted speculation, opinions, and largely anecdotal quotes (a friend of mine had a mechanic who said...). Your mechanic may be a good wrench, but he is grossly mistaken on some of his his facts. First, premium fuel is designed to prevent detonation. Pre-ignition is a mechanical problem and has nothing to do with octane rating.
No doubt that premium fuel is the drink of choice for our turbocharged engines. In certain cases, however (high altitude, cool temperatures, moderate driving style) 89 octane performs just fine. There is absolutely no evidence that there is "build-up of deposits around O2 sensors and catalytic convertors" with lower octane, or that premium is "less damaging to the environment." In fact, the opposite is true; all factors being equal, lower octane fuels actually burns more completely and cleanly. The FTC's official web site makes this point: "As a rule, high octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car’s engine."
Using gas with too low an octane rating is not a good thing; the engine management system, alerted by the knock sensors, will try to retard ignition timing. This causes a lack of power and poor gas mileage. Continued spark knock can be damaging to the engine. The moral to the story? Start with the manufacturer's recommendation but feel free to experiment with. For an easily understood write-up, try this:
http://theserviceadvisor.com/octane.htm
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posted by
someone claiming to be Marc
on
Fri Apr 27 16:43 CST 2001 [ RELATED]
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Actually, premium is not designed to prevent detonation. Without detonation your car wouldn't start or run. Pre-ignition, as I have heard the term used, refers to pre-detonation, detonation happening too early, well before the piston reaches top dead center (TDC). The result is rough running, misfire, poor fuel efficiency and potential engine damage.
Higher octane fuels burn slower and more evenly. This is not likely to result in incomplete combustion. Actually, a faster burn is likely to be less complete.
As a general rule, a higher compression engine requires higher octane to prevent pre-detonation and knocking. A turbo-charged engine usually runs at lower compression when the turbo is not providing much boost (compared to a similar, non, turbo engine) and higher compressions when at full boost (again when compared to a similar non-turbo engine).
The S80 has anti-knock sensors (and probably computerised timing programs) which cause the car to run well on all common grades of gasoline. At higher boost pressures premium will provide more power. Even though the S80 compensates for different octane ratings, Volvo recommends higher octane ratings. The slower and more complete combustion is easier on the engine and as a side benefit, it is slightly safer in the event of an accident involving a ruptured fuel tank because it is slightly less likely to ignite.
Marc
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posted by
someone claiming to be Bart Bobbitt
on
Fri Apr 27 07:29 CST 2001 [ RELATED]
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....is a question I asked Phillips 66, Chevron and one other gasoline company (Mobil or Texaco) last year. Answers were very much alike.
Premium-grade gas (92-93 AKI at sea level) tends to have about 4% more energy per pound (actually BTUs per pound) than mid-grade gas. And mid-grade gas has about the same increase over low-grade.
But within a grade, energy per pound can vary as much as 5% or more across several different companies gas. This is due to the quality of the crude oil refined into gasoline, lot blending at the refinery and tank-farm-installed additives.
Chevron gasoline tends to be somewhat under rated. Chevron's actual AKI numbers are typically 1 to 2 higher than what's on the pump. In fact, most car companies in the Detroit, Michigan area truck Chevron premium gas to their facilities from Kentucky; Chevron ain't marketed in Michigan.
(Note: This may well be one reason why lots of folks don't get the fuel economy in their new cars to match what the window sticker says. They don't have Chevron gas in their local and what they do have has less energy per pound of gas than Chevron does.)
Please don't get on my case about this information. Ask the gas companies yourself and hear what they have to say. I'm just the messenger
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posted by
someone claiming to be Dwight H.
on
Sat Apr 14 03:43 CST 2001 [ RELATED]
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I use 87 Octane, ARCO's finest on my T6. Never had a problem with it. Live near the coast in CA, no problem on hills either. The only reason to use higher grade gas is to keep the pinging down. If it doesn't ping then it's a waste of money to use a higher grade gas. At least in my world that is.
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posted by
someone claiming to be JackFlash
on
Fri Apr 13 07:44 CST 2001 [ RELATED]
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When I bought my new T6, I asked the sales manager the same question. He says that they fill all of their cars from the same on-site tank--containing 89 octane. Here in the D/FW area we generally have a choice of 87/89/93. I have been using 89 with absolutely no ill effects.
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posted by
someone claiming to be Russ
on
Fri Apr 13 04:42 CST 2001 [ RELATED]
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Dave, 87 octane has my S80 running very well for over 2 years. Long drives, city drives, hills, flat desert, hot, cold, every kind of driving. The dealer in my area, SF Bay, recommended it. They run all their Volvos on 87. You may loose a few percent of your HP, but well worth the price if stoplight drags are not your main concern.
Russ
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posted by
someone claiming to be Dave Berger
on
Sat Apr 14 01:44 CST 2001 [ RELATED]
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Thanks Russ and JackFlash,
My S80 will now be using 89 Octane....Thanks, Dave
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posted by
someone claiming to be bob
on
Sun Apr 15 14:15 CST 2001 [ RELATED]
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So let me get this straight.
Based on a couple of responses here in the last few days... from people with qualifications you don't know... you're going to completely ignore the advice and experience of Volvo engineers who built your car and understand every nuance about your engine. You're going to ignore advice and instructions as clearly stated in the Owner's Manual because you obviously think that the factory people only want the snob appeal of being able to state that this vehicle requires premium fuel (93 octane). This will probably make it easier to sell, huh?
And after you dump in a few cans of this and that... exactly how much are you going to save over a year. $100? Your logic blows my mind!!!
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posted by
someone claiming to be JackFlash
on
Sun Apr 15 16:21 CST 2001 [ RELATED]
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Okay, Bob, here are my qualifications: I am an ASE certified mechanic with over 35 years of experience in performance (including OBD-II) applications. I have read my owner's manual, and I see no conflict with the Volvo engineers in using 89-octane fuel. My manual states that for "optimal" performance, 91 AKI fuel should be used, with a minimum of 87. With the current cool weather, low humidity, and light performance demands of my wife's around-town driving, I would be foolish to pay for 93 octane (the premium AKI available here). Those at high altitude might well find that 87 octane works perfectly well. In extreme heat or when I am expecting a full load I might well go for the premium, but I don't see a need for it in most applications. Your point to read the manual is well taken, but it has been my experience that more motorists use fuel octane rated too high than the converse.
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posted by
someone claiming to be Steve F.
on
Sun Apr 15 15:36 CST 2001 [ RELATED]
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I concur with bob. I could never understand why people dont bother to read the owners manual.....and then if they do, they dont understand it....and if they understand it they dont pay any mind to it....???
Why would you spend 35-40K on a car, and then get tight whe its time to put some gas in it?
Guys.....READ YOUR OWNERS MANUALS!!!!
Steve Ferraro
Hoboken, NJ
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posted by
someone claiming to be Jim Miller
on
Sun Apr 15 16:31 CST 2001 [ RELATED]
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It's possible that the use of lower octane fuel will become apparent down the road, say at 80,000 to 100,000 miles. My mechanic says that using the higher octane fuels is better for the turbos - he's been working on Volvos for over 16 years so I'm listening to him!
Jim
99 S80 T6 - 36,000 miles and still purring like a kitten!
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posted by
someone claiming to be Bart Bobbitt
on
Sun Apr 15 23:01 CST 2001 [ RELATED]
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I think it would be nice for us to know why the use of low octane fuel will become apparent after 80K miles. Sounds like your mechanic thinks (knows?) there will be some change to the engine. What's his reasoning, anyway? It's not apparent to us what this change might be. If the use of high-octane gas is important, I think we'd like to know why. Please ask your mechanic to tell you, then please post his reasons. We'll all be a lot smarter about our cars. Thanks.
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