Re: What kind of gas?

You should be using the minimum recommended by the owner's manual, which is

87 octane and nothing more. Any higher octane is a waste of money unless you're getting detonation and higher octane cures it.

I disagree. I say use High grade all the time. I have to anyway on my Wrangler, cause the mechanic who put the new carb on said the manual required it.

My Firebird has a sticker on the filler door that says High Grade is recomended. See Manual for details. So I checked. It said you can safely use

87 but will encounted lower performance, pinging, and hesitation expecially at lower sea levels.

My mechanic said you should always use 93, in almost every vehicle. He's got a

2002 Grand Cherokee Limited, and a 1990 Cherokee.

We use our vehicles for beach driving. We go from here, 200 ft above sea level to right down to sea level. Sometimes you have to pour 106+ octane booster in carbed Jeeps just to get them to run without hesitation. Then when you get back to higher levels, it runs with lots more power with the octane booster in it.

...

Your mechanic is dead wrong. Octane is used to prevent detonation, not add performance as many believe. It can add performance only if a lower octane is robbing the engine performance. The only thing you can do to get better performance by using higher octane (other than adding more compression) is to advance the initial timing. The higher octane will prevent detonation at more agressive timing settings and often a bump your timing will make it run better and have more power, but going too far makes it more difficult to start. Staying with the standard timing settings, and not increasing your compression only requires the minimum octane required. Anything more is just throwing money away.

Now, I've heard, though not experienced, people having detonation while towing vehicles and more octane will certainly help for that.

Octane is not determined by carburation, but by compression ratio. Most newer vehicles are designed to run on 87. Higher octanes can cause carbon build-up in low compression engines. __ Steve .

But that carbon build-up would just cause more pinging and/or knocking since it glows after combustion and will prematurely ignite the air-fuel mixture during the next compression stroke.

Jerry

thanks for beating me to it......you put it a whole lot nicer than i was going to! :-)

it was not meant to be serious.

Bill, the major gas folks were in the news not too long ago saying the only difference is octane, the same 'cleaners' are in all grades of gas.

Yes, they label them only saying the high has it, but that isn't reality, they just omit to label the lower octanes.

Now brand to brand make a radical difference in cleaners, but not octanes.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

"L.W.(ßill) Hughes III" wrote:

Well, any mechanic that sets up an engine so bad it needs 106 octane to not knock or not run well, is out to lunch in my mind.

Or something else is big time wrong somewhere and he upped the timing to compensate....

No way a stock engine needs a slower burning gas than you can get at the pumps.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Yeah, if you can find a transport driver with a degree in organic chemistry and automotive fuel systems, might get some halfway useful information.

Approximately 9/6/03 14:13, L.W.(ßill) Hughes III uttered for posterity:

I dunno, *we* were talking about whether or not there really are more "additives" in the premium grades as opposed to the cheaper ones.... with the obvious answer that there is more octane improver [e.g. MTBE, alcohol]. The issue in question is whether or not there are more detergent additives. Still unconvinced that a tank driver would know which is which as opposed to instructions to "add 50 gallons of the pink stuff" sort.

Approximately 9/6/03 16:50, L.W.(ßill) Hughes III uttered for posterity:

I have a friend who's a truck driver for delivering gas.

He describes it this way,

ALL BRANDS come from the same tanker, once the truck is full the additive is put in to make it (texico, exxon, or whatever). The amount of additive can't amount to more than a few drops per tank full of gas !

SO BUY THE CHEAPEST

Jim

Approximately 9/6/03 18:54, L.W.(ßill) Hughes III uttered for posterity:

I didn't say they were stupid, but I'd be very surprised if they did more than follow instructions. And odd, but one of the oil company engineers who made the statement that *except* where an octane improver has dual use as a detergent there is little difference just happened to be from Chevron.

I know their marketing departments would dearly love to have everyone believe otherwise, but the auto companies also seem to believe that there is more snake oil in those adverts than reality.

This doesn't mean that I personally don't run a tank of premium every now and then, but that also doesn't mean there is a significant difference either.

Not true. Big companies have their direct suppliers. Small ones buy on the open market.

There was a program on the discovery or learning channel a couple of months ago, they cited one pipeline that pumps from a tx refinery to the midwest, all the gas is single brand generic gas. Once it gets to the end of the pipeline it is taken to the individual terminals of the 'brands' where it gets their 'special' additives that make it mid grade and super grades and 'theirs' but not before. Chevron was the only exception that they mentioned, they seem to have some of their own personal pipelines but we don't have alot of chevron stations here in Pa. Apparently one company does all the pipleining for the whole US, or most of it anyway and both sends and receives it to their terminals. Interesting show, I don't think the oil companies enjoyed it much because in one hour it removed the smoke and mirrors that several million dollars and 40 years worth of advertising helped create. I run the cheapest gas I can find in my 98XJ, change the plugs every

70,000mi, add a quart of chevron techron every 10K and at 182,000 mi am perfectly happy. It gives me 22mpg, does good in the rocks and will crawl all day off road. I even smile at people pumping premium in their jeeps and no longer try to convince them it's a waste of money, if your stock 4.0 won't run on regular then something is wrong with it that the higher octane is covering up like bad O2 sensors, knock sensors or other problem, I know too many people that have, 4.0L, 318's and 360 V8 ZJ's that run fine on regular.

Back in the 60's my neighbor owned a Shell station in NJ, I worked there part time in jr high and as it was a 5 min bicycle ride from the house I would go there late at nite to tally up the delivery. Sometimes he would buy Shell and sometimes he would by generic, depended on the price. Shell deliveries came in the daylight, generic came at nite, usually after 11pm :-) Found out it was common practice but back then gas was .17 a gallon for regular and .22 for high test.., cost was .05 and .09 a gallon for generic and .08 and .12 a gallon for 'branded' gas, the consumer price was competitive according to what the next nearest station was selling it for, I remember some of the 'gas wars' that went on, amazing.

Big Daddy wrote in news:3f5aa897$0$43885$ snipped-for-privacy@nnrp.fuse.net:

LOL!

Ya maybe, just before the pinging blows a hole in the top of the piston or snaps a connecting rod....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's