unleaded or permium gas?

[VimyJ]

Does not matter what they call it, premium is usually 91 octane or higher and many times 93. I think it maybe lower at high altitude... like 90. I am sure Q45tech knows why this is.

I'm not Denis but higher altitudes have correspondingly less atmospheric pressure ergo less engine knock conditions.

Use 91 octane or better. The manual states the MINIMUM maintenance necessary to get a brand new car through the factory waranty period. Let that be your first clue about how to treat your J.

[Q451990]

That's right... thinner air slows combustion, so you don't need the gas to be as slow-burning. I vaguely remember Super being 90 octane in Denver, with regular being more like 85.

Heath

[BMW_Dave]

in my '97 J30 with over 100K miles. I maintain the car meticulously and use synthetic fluids throughout. I had never...and I mean never, run anything but premium for the longest time in the J30. However, after reading an article in USA Today recently, where the consensus of a number of auto mfgrs engineers saying you might lose 5% power but not harm your engine,(I was going to provide the link, but you now have to pay for any article over 14 days old) and with premium over 2 bucks a gallon, I have been running regular.

I have seen no difference in performance, possibly a slight drop at WOT, but I'm not even sure about that. Yes, higher compression engines are supposed to benefit from the slower burn of higher octane gas, but when the head engineer for Daimler-Benz states in the article, that he always runs regular in his Benz, with no ill effect, then I decided to try it, and I wish I had the 4 bucks a tank extra that I have spent for years on premium.

The knock sensors on modern cars are so sensitive, that they retard the timing immediately, usually before you even hear anything, and a motor is running at it's most efficient when it is right on the "edge" of pinging, just a hair, under load.

It is also considered a mark of "luxury" cars that they require premium fuel. If I had a turbo car, or a very high compression motor, I would probably buy premium, or mid-grade at the least, but the J30 has been running dandy on regular, and I plan to keep on using it.

I am sure I will get flamed for this, but most on the board that insist you run premium, or suffer dire consequences, are the same ones that change their synthetic oil at 2,500 miles...what a waste of money and resources...it's your cash, do what you will.

Oh, and lastly, I check my mileage at every fill-up...same as I got with premium 18 to 22 MPG.

http://www.caranddriver.com/ar...=3604

[Jesda]

[Need4Speed]

All I gotta say is: Check out the price of a replacement engine (don't forget to add in installation labor too) and frequent synth. oil changes and premium gas prices don't sound so bad.......

-Andy

[Aus94Q45]

Just read an article this morning on gas costs. In the 1950's gas was about $.25 to $.28/gal. These prices lasted until the 1970's and the oil crunch that rasied gas to about $.50/gal. The author's point was that in 1950's dollars the price equates to about $2.08/gallon. So, while the current prices are high, they are not that out of line with what we all considered as "cheap" way back when. Premium here runs about $.15/gal more than regular. While I don't like it, I will spring for the extra $3 per fill-up over regular . . . . heck I can't buy a burger for that! Also, I suspect that we are at the next level and shall never see $1.25/gal. premium (ie. two or three yrs ago) again. While the price is at a record high, the consumption is unabated, and continues at a record pace. Thus, the gas giants know that people are willing to pay more. Only time and expense will curb the general population's thurst for the giant SUV's and V-10 trucks.

[Q45tech]

"ethanol is a renewable resource" Not really since the amounts of fertilizer, pesticides, and diesel to farm are all made from oil.

It takes much more energy to make a pound of corn, turn it into ethanol and transport it from the ethanol plant to refinery than to just substitute more oil.

"It now appears that consumption of U.S. corn during the current marketing year will exceed the record crop of 2003, resulting in a draw-down in stocks of 186 million bushels. It also appears that the market for U.S. corn could expand during the 2004-05 marketing year. Domestically, that expansion will likely come from continued growth in ethanol production. Corn used for that purpose totaled 706 million bushels in 2001-02, 996 million bushels last year, and is projected at 1.15 billion bushels this year. With additional expansion in ethanol production capacity, use could increase another 100 million bushels in the year ahead."

About 12% of all corn is used in Ethanol production currently, with the MTBE phase out it will jump to 30%.............we will lose a major source of foreign exchange!

To create energy independence:It would require ethanol increases of 22 times, More than quadruple corn production and increase corn to 97% of all harvested acres of every crop.........grow nothing else in US except corn.

http://www.nass.usda.gov/ky/B2003/p105.pdf

My analysis is oil and oil components are $97-$111 per planted acre with a yield of 95-150 bushels per acre so petro cost is at least 75 cents per bushel or 25% of total cost.

So a feedback loop would be created since only fuel [for tractors] can be made from Ethanol. But tax payers would have to pay for new non diesel tactors which would get half the mpg.

At a certain point the increased planting would need more oil imports. Just for fertilizer and pesticides.

http://tonto.eia.doe.gov/oog/info/twip/twip.asp

[szh]

most of post deleted for brevityI am sure I will get flamed for this, but most on the board that insist you run premium, or suffer dire consequences, are the same ones that change their synthetic oil at 2,500 miles...what a waste of money and resources...it's your cash, do what you will.

Oh, and lastly, I check my mileage at every fill-up...same as I got with premium 18 to 22 MPG.

http://www.caranddriver.com/ar...=3604

Like your own sig says:

"Never argue with an idiot ..."

So, I won't say anything!

[Jesda]

If youre going to buy a car new, drive it 100k and let it go, or youre a leaser, then I can see not wanting to spend extra.

But if its your darling hard-to-replace first-generation Q45, you'll want to keep its last day on the road as far away as possible.

-Jesda

[boomstriker]

It is true that with the high compression and aggressive timing, the Q and the J should get the higher octane, just as a turbo car or any high performance engine. Sure there are safeguards built into the system to detect the knock and retard the timing to prevent the damage to pistons and lower end.As Dave said, max power and efficiency is just before detonation, but power and efficiency drop and damage can occure with the onset of detonation.That being said, if you're going to use the cheap stuff, a simple cure is to just retard the base timing from the factory setting by 2 or 3 degrees, or untill the knock goes away with the fuel of choice.I've done this to both my Q and J with no ill affects to idle or drivability.My wife uses the Q as a daily driver so I'm not real concerned about the 6 or 8 HP loss, and if my mileage dropped a point or two, I sure didn't notice.If you don't know what spark knock sounds like, or you don't have the ability to retard the system with a T light, then just stick with the good stuff.But, I wouldn't recomend running the cheap stuff without doing this mod, especially in the summer heat.Kirk

[cousteau77]

Would there be any noticeable effects of switching from 93 octane to 91 octane, which is a few cents cheaper?

[szh]

Would there be any noticeable effects of switching from 93 octane to 91 octane, which is a few cents cheaper?

IMHO, you would be fine with 91 ...

Z

[Q45tech]

If $4.50 a week [tankfull] or even $235-$260 per year is significant to your driving budget..........time to rethink your car selection.

We bought a nice paint/interior 92Q that had the motor carboned up ----chunks on 3 pistons and holding valves open [no compression] for $750. Oh it was the wife's car she always drove in town and always used regular.

Not saying it will happen just that it has happened and could happen........probably takes the combination of abuse and many years and miles.

Retarding the base timing will contribute to inefficiency especially at cruise allowing incomplete combustion into less carbon dioxide ergo the carbon build up.

http://www.insultmonger.com/swearing/yiddish.htm

[elwesso]

Nice link dennis!!!!!

[Jesda]

Im confused. Im supposed to learn yiddish?

[boomstriker]

I've never seen a properly maintained VH have any amount of carbon on the crowns or valves.Mine was very clean at 130k.I would suspect a combination of oil from leaky valve seals and rings, a life of babying and extremely high mileage to get that bad.

Retarding the timing to eliminate knock is not going to make the engine less efficient or produce more emissions to the point where it will ever be detected.We're talking 2 or 3 degress here. If the spark occurs as early as possible without knocking at the highest coolant and ambiant temps, it will be just fine.

[Q45tech]

Or the laungage of your choice. It's the thought that counts not the lanuage it's delivered in:http://www.insultmonger.com/swearing/index.htm

The point is/was everything has consequences and retarding the timing is not free of downsides................Damn, Sacre bleu!, Verdammt, Kuti ka bacha, Chikusho!

[elwesso]

Well this clears it all up, Dennis is human and has a sense of humor!!!!

I guess that being an alien or robot is over with....

[Jesda]

Like hell it is. The bet's still on!

[BMW_Dave]

O.K. here is the link that, after reading, helped persuade me to try the 87 octane route:

http://www.usatoday.com/money/...x.htm

A special note for "szhosain", you have a new M45, I don't blame you for sticking with "premium" and I will admit a little "guilt" when I put the 87 octane in, but until someone shows me real quantifiable proof that I am doing some "harm" to my engine, I will continue to save $4.00 a tankful.

I will also continue to run my Amsoil 5w30 for a "minimum" of 7,500 miles (changing my Mobil 1 or Amsoil filter at 6mos, topping oil off, and using an Amsoil foam air filter). There is always so much talk on the board regarding oil changing regimens...but very little about how important oil and air filtration is to keeping your oil clean.

Many seem to forget the original Mobil 1 ads which said you could run it for 15-25K miles...Amsoil guarantees 25K miles or 1 yr with a filter change in between. Mobil chickened out for "liability" and probable "profitability" reasons, but still recommend that you can take it to the mfgrs "maximum, i.e. non-severe service" mileage.

One caveat which I failed to mention, I put a bottle of RXP in about every 4th or 5th fill-up...I don't usually put much stock in fuel additives except Techron, but this stuff rocks! I am truly convinced that it has eliminated any carbon buildup on my piston crowns, which definitely leads to absorption of fuel and detonation/knocking. A link to their site:

http://www.rxp.com/master.htm

By the way, the rest of my sig reads, "Always remember the law of diminishing returns."

[Rex]

Use only premium..... You will get better gas mileage, your car will perform better (a LOT better), and its just better......

Look at it this way.... Most places only charge 10c more for premium over regular (at least in IN), so if you fill up 20 gallons, it only saves you $2 a fill up, and say you fill up once a week, thats $8 a month, $96/yr...... pretty insignificant if you ask me, especially to keep your car healthy and happy!

The engine can only compesate for so much pinging..... what it does to do that is it retards the timing (essentially lowering the compression ratio), and that means MUCH lower performance, and lower gas mileage...... You may even get enough better gas mileage over premium/vs unleaded to offset the costs (that may be pretty drastic), or at least close......

Such wisdom from such a young man.

Drinking Sam's Choice would save you more (depending on your cola intake)Buying your clothes at WalMart/Value City/Target/KMart would save you more money (Is KMart even in business?)Clipping coupons would save you more on your groceries (assuming you by name brand groceries that use coupons, the generic crap doesn't)

I could go on and on, but Wes made the point.

[elwesso]

Sure, you may only have to use and change amsoil once a year, but how long do you think you can get away with that..

I can GUARNTEE you right now that if Dennis for example used amsoil for his once a year oil changes, his engine wouldnt be in the condition it is in right now, hell i would probably say it wouldnt be running...

Its just not worth it. $120/year gets you 4 mobil 1 changes! Its not that big of a deal, especially when it comes to an engineering masterpiece of the VH or VG..

I dont really care if you continue to treat your J30 as you would a lesser car. I would ahve no problem doing what your doing to a honda, because it seems you just have to keep oil in it and they keep running... But most of us here realize the engineering masterpiece we drive and want to keep it for a long time...

[elwesso]

Just another point im trying to make:

Trying to save money on cars by using inferior products will almost ALWAYS cost you more later....

[maxnix]

Quality of oil doesn't change the engine's tolerances nor the rate of contamination of the oil with combustion blow-by products.

Better to use conventional and change twice as often if you can avoid operational temperature extremes.

[szh]

O.K. here is the link that, after reading, helped persuade me to try the 87 octane route:

http://www.usatoday.com/money/...x.htm

A special note for "szhosain", you have a new M45, I don't blame you for sticking with "premium" and I will admit a little "guilt" when I put the 87 octane in, but until someone shows me real quantifiable proof that I am doing some "harm" to my engine, I will continue to save $4.00 a tankful.

Here is a quote from that article you mentioned:Quote »Actually, the price debate is nearly worthless. At 20 cents more for premium, pumping 20 gallons of it instead of regular would cost $4 more. Annually, that's a difference of $171 for a vehicle that averages 14 miles per gallon — as some big sport-utility vehicles do — and is driven 12,000 miles a year.[/quote]So ... don't you think that the difference is relatively minor - even with regard to today's higher gas prices? If you can afford to get a high-performance, high-end car, then this relatively minor cost issue per year should not be a reason to make your car strain more and possibly create problems. For example, the anti-knock sensors may not help out in severe load conditions (like if you go uphill for longer distances in high gear).

I will gladly say that if the car mftr says "use regular", then using premium seems silly. However, I will also gladly say that if the car mftr says "use premium", then using regular seems silly. 'Nuff said!

Z

[elwesso]

Very well said Z... That is really what it comes down to.....

YOU WANNA PLAY YOU GOTTA PAY!

[BMW_Dave]

Quality of oil doesn't change the engine's tolerances nor the rate of contamination of the oil with combustion blow-by products.

Better to use conventional and change twice as often if you can avoid operational temperature extremes.

The quality of oil (read synthetic) does change the engine's tolerances indirectly...it is well known that the molecular structure of synthetics promote better ring seal reducing blow-by. Furthermore, synthetics offer "boundary" lubrication, i.e., they tend to cling to metal surfaces whereas "dino" oil, by and large, tends to drain off.

Continuing on the subject of "blow-by contamination", all synthetics have much higher TBN/total base number levels (Amsoil is the highest and ergo the safety in "extended drains", Mobil 1 and others are respectable, and blow "dino" oils away).

However, my biggest reason for using synthetics are the radical rises in viscosity levels in "dino" oil after only a few hundred miles.

Conventional oils are awesome lubricants compared to what they were even 10 years ago, but they are so inferior to synthetics that even GM is planning on factory fills in all (not just Corvettes) within a couple of years. I would predict that Infiniti will also follow suit as has Aston-Martin, BMW, M-B, Porsche, to name a few.

[BMW_Dave]

Originally posted by maxnix: But the way we do it in this country consumes even more petrochemical resources for fertilizer and pesticides. It's an insane policy.But no one's complaining about using genetically modified corn in the alcohol, yet.

Brian, I'm not targeting you, and I am certainly no member of the Sierra Club, but if you are concerned about consumption of petrochemical resources, then why would you promote needless oil changes? Not trying to pick a fight, just curious about your reasoning?

[maxnix]

Don't remember the quotation (are you sure it was me?), but first you need to define "needless oil changes". I say that because it degrades upon first use and continues to do so upon subsequent uses. The only question then is how much degradation will you accept?

[szh]

Brian's comment had to do with how ethanol is produced in this country.

Z