Pain at the pump octane

[Shadow Catcher]

Some of the sharpest individuals I know of are on this forum so I will ask.
It is becoming increasingly painful to fill the tank in my Outback with a 3 L H6 which wants premium but gets mid grade.
I started looking into octane boosters and specifically going after the MSDS sheets to find out exactly what is in each of them. The main ingredient usually 98.5 to 90%, is kerosene. The rest is usually MMT Methylcyclopentadienyl manganese tricarbonyl or in a few cases ferrocene, both without going in to the chemistry, manganese. It is not economically advantageous to use a commercial octane booster, cost eats up the difference.
It would appear that kerosene alone is an octane booster and I use K1 kerosene to heat the garage during the winter using an Eberspacher diesel heater.
A will kerosene harm any of the components in the engine?
B is there a way to tell if it's working, the engine management system keeps it from pinging no matter whether I use regular, midgrade, or premium gas. My thoughts being monitoring some aspect of the OBD II with a scan gauge or OBD scanner.

[Ratkity]

I don't know if this pertains to your vehicle or not, but the newer cars have a computer that regulates fuel intake. Straight from the head mechanic's mouth at the Toyota place where I got my 2006 Rav4 (brand new): "Your car runs better on regular gasoline, don't bother with the high octane stuff. Reserve that for high performance engines." He said this in front of a new car class (yes, immageek and attend those things.. hey, they fed us!).

Hugs,
Ratkity

[wagondude]

The 3.0 Subaru is recommended for premium fuel, for those that don't know. If you have a scan tool, you should be able to watch timing advance to see if there is any difference. It would probably just be easier (cheaper) in the long run to use whatever you want for every day driving and fill with the high octane when towing.

[mechmagcn]

For the most part the manufacturers require premium fuel to meet the rated horsepower specs. As long as the engine management will keep the engine from pinging, there is no reason to run premium. A lot of vehicles will actually get better fuel economy on regular!

[Rock]

All modern cars have an octane sensor - to know the amount of alcohol in the tank if nothing else. So as someone mentioned the control computer will adjust for the lower octane - no harm done. You just won't get the advertised horsepower and you might not get the same mileage as the engine is not running at it's optimum tune.

P.S. - Simultaneous post - you will want to listen for pinging but it shouldn't.

Eric

[aggie79]

I had a 2002 VW Passat with the V-6. It called for premium fuel, but all I used was regular unleaded. I put 220,000 miles on it without a problem. (The transmission went out at that point and I decided to "retire" the car rather than invest $4000 for a rebuilt transmission.)

I do disagree with one previous poster. Whatever fuel you use, stick to one grade and don't switch. While the car will immediately adjust timing and other variables dependent upon the vehicle, the engine contro unit "learns" driving habits over time and adjusts the data tables.

[Shadow Catcher]

I have gotten a further clarification from the Outback email list. premium is required for the turbocharged engines and recommended for the H6 so I can use regular with out hurting the engine. But this still leaves the question can I use kerosene to boost octane with out hurting anything.

[caseydog]

I have a twin turbo V6 that "requires" 91 octane. In the heat of summer, I run premium, but in cold months, I run mid-grade. Cold weather allows your engine to run on a little lower octane fuel -- maybe one or two points. There is a mathematical formula on the web somewhere that you can use to figure out just how much lower you can go.

CD

[caseydog]

I have gotten a further clarification from the Outback email list. premium is required for the turbocharged engines and recommended for the H6 so I can use regular with out hurting the engine. But this still leaves the question can I use kerosene to boost octane with out hurting anything.

Kerosene is a pretty waxy fuel. I sure wouldn't put it in any gasoline engine of mine.

CD

[pete42]

I would wonder what it would do to the catalitic convertor (spelling doesn't count).

used kerosene in a diesel in the winter before to thin the fuel.

isn't higher octane to keep the fuel from burning at a lower temperture causing the dreaded ping?

pete

[Yota Bill]

kerosene can detonate from compression, which is why it works in diesel engines (the fuel is put in the cylinder after the air is compressed)...in a gas engine, the fuel is mixed with the air, injected into the cylinder, and then compressed. This could cause pre-detonation if kerosene is used, resulting in major damage (possible, not necassarily probable)

If you did run it, and damage does occur, you can kiss the warrenty goodbye as well. Pre-detonation damage is pretty easy to see and find the cause.

[absolutsnwbrdr]

I have a 3.0 H6 and it typically sees either 89 or 91 octane. You are right about the turbo Subies requiring 93, but the H6 isnt as demanding. Its just a higher compression engine than the other naturally aspirated boxer engines.

A lower octane won't hurt it, but you could notice a minimal drop in power. Also, the higher octane works to prevent "knock". If while running a lower octane, you notice the engine knocking, or pinging, it wouldnt hurt to top off the tank with a higher octane, or dump in some octane booster.

When towing, I run at least 91, just because the extra strain on the engine.

BUT.... when considering adding the octane booster, do the math and realize that unless the mid or high octane fuel is substantially higher cost than the low grade, you may be actually spending more money to dump in the bottle of additive - if the high octane is only 0.20/gallon higher, and you fill up from empty, you're only spending another $2.80 more (based on 14 gallons) for an entire fill-up compared to $5.00+ for the octane booster.

[Wolffarmer]

As Casey Dog said engines can get by on lower octane fuels in colder weather. Also higher the altitude the lower you can burn. My 1974 BMW motorcycle gets the cheapest crap until I get down to about 1000 feet above sea level. It will start to ping then. So Slow cowboy and I can probably get by with just about anything. Here where I live I just laugh at the people putting the hight priced stuff in their chariots. I am at about 4400 feet.

Also the gas we get now days is not like the stuff from my youth. Use to be if you left some gas out in a pan in a few hours it would be all dry. Now days there will be an oily gunk left in the pan that will not evaporate in the foreseeable future. From what the oil people say if the gas was like it was way back when, it would cost a heck of a lot more than it does. And with fuel injection and computer control, vehicles can burn it just fine. Though a carburettor engine gets about 10% worse millage than it would on the old stuff. AS far as diesel/kerosene making a motor detonate, in my experience it doesn't. I have put up to about 10% diesel in a gas motor and it ran just fine. And once I saw a gas farm truck get filled with about 90% diesel and it was still running and pulling a full load. Smoked like the devil and we didn't dare shut it off until the driver got back to the shop. That was sure funny.



So, in my book it boils down to, the higher the elevation, the lower the temps the less octane a motor needs. Also most people that buy the high octane stuff, are wasting their money.

My 2 cents worth.

Randy

[del]

My thoughts on octane, run what the engine is designed for. To run the lower octane petrol the computer retards the timing, which make the engine run warmer, and also decreases mileage. The lower mileage negates your savings, not to mention possible engine damage. In theory kerosene would increase octane. Getting the right mixture would be the challenge, not to mention it is more expensive, at least here.
Yes compression ignites the fuel in a diesel engine, but a low compression diesel is 20:1. A high compression petrol is 14:1, very different engines, in many ways.

del

[Shadow Catcher]

Note that in my origional post I said that Krosene is usualy 98+% of any after market octane booster (from looking at MSDS sheets) and that it has an octane boosting property all its own. Quantity used is between 6 to 16oz used to "treat" 20 gal. Most of the manufacturers claims are smoke and mirrors judging by the range of, this is what might be in it, MSDS information. One lists that the kerosene content is 80 to 100%. I will not be buying after market booster it is less expensive to pay the difference for premium.
I am going to be buying an Ultragage (less expensive than a Scangage) to monitor gas milage coolent temps and one of the things it can monitor is spark retard. So I will be playing with this.
Slow, the car is an 01 and is paid for and only has 104,000 miles I will get another 100,000 to 200,000 miles on it unless Subaru imports their diesel.