What gas to run in 6.0?

mrusk · June 2, 2003

I am just wondering what gas you guys are running in your 6.0 motors.

matt

Bob G. · June 2, 2003

I run 89 only cause the local "no attendant, stick my card in the slot and fuel up 24/7" station has one gas and one diesel pump and the gas is 89. If I get gas elsewhere, I buy 87. The price of the 89 is cheaper than the other convenient mart stations 87.

Bob G.

timk49 · June 2, 2003

When I ,m going to tow I use 89 or 91. Daily driving 87.

Shaners · June 2, 2003

87 Octane all the time here... I run it because it's cheaper, and because my dealer says that there is no reason to run anything higher than that.

MarkD · June 2, 2003

Run as low of an octane as possible without knock/spark rattle under load.

AlanTDickey · June 3, 2003

MarkD's answer comports with what an engineer told me once. I have not been able to confirm his rationale. Can anyone tell me if it is correct. It went something like:

Octane is a knock suppressant that prevents the cylinders from firing too fast - and before the piston returns to the proper position – i.e., knocking. It does this by REDUCING (not increasing) the volatility of the fuel. This knocking problem is more common the higher the compression ratio is on an engine – the higher the engine’s compression ratio, the more the engine needs a higher octane (less explosive) fuel. Thus, a necessary evil for a hot, high-compression engine is to lower the explosiveness of the fuel the engine consumes. So, you are just reducing your power when you use a higher octane than you need. Of course, this runs contrary to the common conception that higher octane gives you more power.

Is that why you don’t want to use higher than the minimum octane ????

BDBWTE · June 3, 2003

87 is all the HD see's the only time it had 93 was when she was new and a free tank of gas was provided.

Fuddrucker · June 4, 2003

MarkD's answer comports with what an engineer told me once. I have not been able to confirm his rationale. Can anyone tell me if it is correct. It went something like:

Octane is a knock suppressant that prevents the cylinders from firing too fast - and before the piston returns to the proper position – i.e., knocking. It does this by REDUCING (not increasing) the volatility of the fuel. This knocking problem is more common the higher the compression ratio is on an engine – the higher the engine’s compression ratio, the more the engine needs a higher octane (less explosive) fuel. Thus, a necessary evil for a hot, high-compression engine is to lower the explosiveness of the fuel the engine consumes. So, you are just reducing your power when you use a higher octane than you need. Of course, this runs contrary to the common conception that higher octane gives you more power.

Is that why you don’t want to use higher than the minimum octane ????

That is exactly right. Some people call it detonation or pre-detonation. Fuel actually ignites before the piston is up where it should be for maximum power/compression. I ride ATV's and have a few friends that race. They have had their engines built up so the compression ratio is really high, 13-1, or so and they have to run racing fuel with octain between 106 and 112 so they do not destroy their engines with all the pre-detonation that would happen with a lower octain fuel.

Just my .02

Truckman031 · June 4, 2003

I would recommend 87 octane.

AlanTDickey · June 4, 2003

Thanks for the confirmation Fuddrucker.

It's interesting then how the gas stations market the highest octane fuel as high performance fuel, when it simply reduces power and gas mileage for those without ultra-high compression engines. They make octane sound like nitro or something, when it actually makes the fuel less combustible.