Gas grade: Regular, Mid or Premium?

[mm58]

I've read various posts about leaded vs. unleaded, and I have just been using unleaded with no lead additives.

But I have seen nothing about which grade of unleaded is best for the Pinz. The person who I mine from, told me to
always use Premium grade but didn't really say why.

What's the consensus here? With gas prices being what they are, are there any negatives to using plain Regular Unleaded vs. higher octane?

Thanks

[bonefish635]

You'll get no increase in performance from anything beyond the lowest octane level on the stock engine.

Over here (in the UK) the premium petrols are said so have engine cleaning chemicals built in, as well as a higher octane rating, but whether any improvement is measurable or not, i don't know.

I had an old BMW M5 once (e34 model) and I was convinced I could tell the difference between standard and premium in it, but in nothing else before or after. Over here standard is 95 octane and premium is 97-99 so it's a real small gap.

To end on a plus note (for anyone in the US), over here we're paying just about £8 per gallon now, which would be $13 a gallon to you (slight difference in gallon size I know).

(Sigh).

Tony

[mm58]

Over here, regular is sold as 87 octane.
Wow, $13 dollars a gallon! Our streets would be deserted if that was the case here.

[berger]

The Octane ratings used in Europe are different than those here in North America.

In the United States, pump octane is an average of 2 ratings, research octane (RON) and motor octane (MON). If you look at any gas pump in the United States, you will see a yellow sticker that says "octane by R + M / 2" That is the basic formula for an average. These 2 numbers mean different things. You could make an analogy to that of a blood pressure reading (systolic and diastolic). Research Octane number is always higher than Motor Octane number.

In Europe, they only report the RON. You may hear people discussing that in Europe, the octane is higher. Well, that is not exactly true. You see, in Europe, you might find 96 octane at a local gas station. (wow 96, highest we have here is 94). Well, that 96 is equivalent to 92 here in the States.

[westernair]

No fuel savings and no improved performance in my truck when using higher grade fuels. I do keep my spare can filled with premium as the additives seem to keep it from going bad over a longer time

[Stekay]

No fuel savings and no improved performance in my truck when using higher grade fuels.

You might even notice a DECREASE in performance and mileage as the higher octane fuel burns slightly slower decreasing cylinder pressure. If you took advantage of the increased octane as modern cars with knock sensors do by advancing the timing to just before detonation is sensed, you probably would feel some performance and mileage increase. Remember, octane is only a measure of resistance to detonation.

[berger]

Good read here....

http://www.state.mn.us/mn/externalDocs/ ... eFacts.pdf

Octane Facts
• Knock occurs when cylinder pressures are high. It is normal for an engine to ping a little at full throttle
because cylinder pressures are very high at full throttle. Engine knock, however, should not be ignored
since it can result in serious damage to the engine.
• High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when
cylinder pressures are high.
• If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in
switching to higher octane gasoline.
• If your engine knocks or pings, it does not necessarily mean something is wrong with the gasoline. It could
be a problem with the engine’s electronic control systems, ignition timing or exhaust gas recirculation. On a
high mileage engine, a carbon build-up in the cylinders can increase cylinder pressures and cause knock.
• Almost all of today’s new cars have fuel-injected engines that need to use gasoline with a detergent additive.
They do not necessarily need high octane gasoline with a detergent additive. Generally, new automobiles
need high octane gasoline only if the manufacturer recommends it.

Octane Myths
• High octane gasoline improves mileage.
In general, if your car is designed to run on 87 octane gasoline, high octane gasoline will not improve
mileage. If switching to high octane gasoline does improve mileage, you might find that your engine, or its
control systems, need repair.
• High octane gasoline gives quicker starting.
No, it doesn’t.
• High octane gasoline increases power.
If your car is designed to run on 87 octane gasoline, you shouldn’t notice any more power on high octane
gasoline. Again, if it does make a noticeable difference, your engine, or the engine’s electronic control
systems, may need repair.
• High octane gasoline has been refined more – it is just a better product.
Additional refining steps are used to increase the octane; however, these additional steps do not necessarily
make the gasoline a “better” product for all engines. They just yield a different blend of hydrocarbons that
burn more slowly. The additional steps also increase the price.

[Jimm391730]

And the additives that increase the octane rating takes space that would otherwise be gasoline (adding and ounce of addtives to a gallon of gasoline means that there is one ounce LESS gas per gallon) so in an engine that cannot take advantage of high octane (because the compression ratio is low, like the Pinz) just gets very slighly less actual FUEL to burn in each stroke.

Nothing but advertising hype says that more expensive gas has any more cleaning agents or stabilizers for storage than cheaper grades of gas. It is a good idea to cycle the fuel in your jerry cans into the tank and refill the jerry cans with fresh fuel at least once a year. I occasionaly add Stabil to the freshly refilled jerry cans (when I think about it) as it seems like it would be a good idea but not always; I've never had a problem either way. Fortunately the European jerry cans seal so tightly that the fuel can't leak vapors out or get addtional air in; my feeling is that O2 from the air is what causes most of the fuel storage issues -- the fuel oxidizes as it gets access to addtional oxygen. If O2 can't get in, the fuel can't oxidize as much.

Save your money, buy the lowest rating you can. This doesn't mean using the cheapest gas; some unscruplus stations have been caught adding water or other "thinners" to gas, and poor gas almost always shows up as poor performance and possible damage to the engine.

[mm58]

This is all great info guys...thanks!

[edzz]

IMHO, different grades of gas may contain less alcohol.

I believe that for my (our) uses less alcohol is better.

[djw]

over here we're paying just about £8 per gallon now, which would be $13 a gallon to you (slight difference in gallon size I know).

(Sigh).

Tony

Since the Imp Gal is +20% more than ours, it makes it all better (i.e. your equivalent to USD $10/gal). Much more tolerable

Essentially a buck per mile for fuel.

[Jimm391730]

Essentially a buck per mile for fuel.

I hate it when you say it like that!

[audiocontr]

A factoid that I always found of interest revolves around gas in/gas out of the major pipes servicing the country - As a supplier adds gasoline at the base of the piping (say Galveston) they can immediately withdraw fuel at the other end (say Maine). Its not guaranteed to be their fuel, but simply the same described octane.

The additives (added after withdrawel) make it their secret sauce

[Jimm391730]

Another gas factoid: GM trucks in Chevron gas to use for fuel efficiency testing. I guess they feel that Chevron has the right "secret sauce".

[Jim LaGuardia]

Plain and simple, premium gas burns cooler/longer resulting in lower cylinder head temperatures(better for valve seats and guides).
Gm uses Chevron gas because of the Techron additive, it keeps the CMPFI (central multi-port fuel injection) injector poppets clean and lubed without melting the plastic parts.