Re: midrange octane fuel

Here in the midwest, most of the mid-range gas is 10% alcohol. (It's corn country) Mid-range is usually 3 to 10 cents cheaper because they don't put on as much road tax per gallon as regular gas. Most of the no-name stores have 89 octane that has alcohol, but a few of the name- brand chains (like BP) do not.

It all depends on what car I'm adding gas to. I have a 4.0 Aerostar that is notorious for detonation (yea, I need to clean the carbon out of the combustion chambers) that I sometimes put in 10%, but my other daily drivers get 87 octane.

My 71 Cougar needs 93 octane.

snipped-for-privacy@yahoo.com wrote in news:489cecfa.331411937 @news.astraweb.com:

Or it costs little to sell and helps create a marketing gap between high and low priced gas...

If I come across a station that's having its tanks filled, I ask the truck driver which tanks he's filling (I'm weird). The answer is always "premium" or "regular" (usually "regular"). NEVER has any driver EVER said "mid-grade". This leads me to suspect that "mid-grade" is just a blend from the two other tanks. I should specifically ask next time...

My understanding is that that is exactly the case, at least in the US.

** Posted from **

Reportedly, the octane rating for a mix of two octane ratings is proportional -- IOW, 1/2 tank of 87 plus 1/ tank of 89 equals one tank of 88.

Pete

Yep, mid grade is a blend of high/low done right in the pump.

FYI DON'T buy gas if the tanks have just been or are in the process of being filled. It's a good way to get a load of dirt/water in your tank!

"Steve W." wrote in news:g7kc2s$52r$ snipped-for-privacy@aioe.org:

There is a station in the next town from me that has its tanks refilled at least twice a day. It's next to a major highway, so its volume is enormous. I suspect this station's gas doesn't sit long enough to allow any water accumulate in the first place.

I still would try to time it between the dumps. I've seen many cases of plugged filters and crappy performance due to bad gas issues.

Yes, I did one time when for some strange reason it was cheaper than regular. The only thing wrong with using a higher octane than needed is that it is a waste of money (ordinarily). If it is, under funny situations, cheaper than regular, go for it.

Yup....for my 99 Taurus 3.0 Duratec. It performs noticeably better on 89 vs 87. 91 works no better than 89 in it.

87 in the 03 F150 4.2 V6...AND the '05 Jetta 2.0 (which probably could whup the Taurus in a road race)

--Don Don Byrer KJ5KB Power & Glider Pilot Guy kj5kb-at-hotmail.com

"I have slipped the surly bonds of earth; now if I can just land without bending the gear..." "Watch out for those doves..."

This is probably true of many vehicles. In many parts of the country the stuff in the gas stations regular tank is 83 octane gasoline - that is the octane of regular coming from the refineries. It is supposed to have 10% alcohol added to raise the octane to 87 (in most of the US regular without ethanol is no longer available). Because of the sudden large demand for ethanol it is often the case that ethanol is not being added to regular and so the octane is not as high as it is supposed to be. What has happened is the entire refining industry has degraded "regular" gas (degrading=mucho$$$$$) in the expectation that ethanol will raise the octane back to where it is supposed to be. There are several problems with this. One is because of the huge demand for ethanol often supplies are short and your regular gasoline simply doesn't have the octane it is supposed to (it doesn't have as much ethanol added as it is supposed to). The other factor is that even when the ethanol is added in the correct amount its impact on octane varies from one vehicle engine to another. This is because engines are being designed to run on a different fuel than what is actually available at the pump (except flexfuel vehicles).

The fact that ethanol effects different engines octane requirements a wide variety of ways is a well recognized property of ethanol. The EPA knows this and so do the auto manufacturers. The EPA deals with this by simply excluding ethanol from its test procedures. EPA mileage test are done with 96 RON fuel (no ethanol allowed). Another requirement by the EPA in mileage estimates is that the use of

91 octane RON doesn't reduce mileage by more than 3%. This rule was added about 10 years ago for vehicles that are certified by the manufacturer to run on regular gas. The reason this rule was instituted is because it became clear to the EPA that the presence of knock sensors and advanced fuel management was making it possible to design engines to run with best mileage at the test octane of 96 RON (and still run OK with the actual lower octane fuel available at the pump). There is a provision in the clean air act that allows the EPA to create new rules if they perceive that the MFG's are trying to "defeat" the tests. So they instituted a new rule that says your mileage can only increase by 3% if you use 96 RON instead of 91 RON. So there is a codified limit built into the standards to which engines are built that sets a limit to how much your mileage can increase from 91 to 96 RON fuel. Of course YMMV.

It is also an EPA requirement that new vehicle mileage tests be done without any ethanol in the gas. This is because it is recognized that ethanol behaves much differently than gasoline with respect to octane and fuel mileage. The RON octane number for ethanol is 90. These tests that are required by federal law are used for the new vehicle sticker mileage estimates and for the manufacturers CAFE requirements. The outcome of these tests mean millions of dollars to the auto manufacturers and vehicle design is built around these tests. The logic of the EPA on using fuel that is in fact not what is found in the local gas station pump is that the Clean Air Act from which all these standards are derived was passed many years ago and to change the standards for the fuel requirements to reflect what is actually being sold today would amount to changing the law after the fact. It claims that if it would include ethanol in its testing procedure it would give an unfair advantage to some engines (this is undoubtedly true) and thus the solution they came up with is to bury the entire engine manufacturing collective heads in the sand.

So those people who claim that you should pay attention to the auto manufacturers recommendations on octane - they simply don't know what they are saying. The federal law specifically prohibits manufacturers from making real world test with real world gasoline and publishing the results of those tests to the public. Subject to severe penalties the manufacturers are required to test their engines and publish the results using a fuel that isn't available at any gas station and hasn't been available for almost 30 years. And anyone who thinks the mfg.'s aren't designing to meet the specific requirements of those tests is completely naive.

-jim

bending the gear..."

----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==----

The #1 Newsgroup Service in the World! >100,000Newsgroups

---= - Total Privacy via Encryption =---

Yep, in my area the low grade is 85, midgrade is 87 and premium is

1. My truck's manual says to use 87 so I use the midgrade.

Derek

wow

Yep, in my area the low grade is 85, midgrade is 87 and premium is

1. My truck's manual says to use 87 so I use the midgrade.

Derek

Is that somewhere in high altitude??

mg

** Posted from **

Sounds like it is -- However, I have read somewhere recently that at least on vehicle manufacturer recommends going with the recommended octane regardless of altitude.

What would be bad, esp in hot weather, is to have a tank full of the

85 octane and then come down out of the mountains into the hot valleys

-- That's definitely a time to leave some room in the tank for some high octane to bring the mix up closer to regular 87.

Pete

I am about 6000 feet. I was told that 85 is good enough at this altitude but the dealer said run at least 87 no matter what so that's what I do. I ran 91 for a couple months and noticed no difference in economy or power.

I am about 6000 feet. I was told that 85 is good enough at this altitude but the dealer said run at least 87 no matter what so that's what I do. I ran 91 for a couple months and noticed no difference in economy or power.

I asked because I used to live in Denver and that was how the gas was rated. I ran 85 in my Integra and occasionally got a check engine light, but only with Conoco. No other brand was a problem.

mg

** Posted from **