Gas: Leaded vs 100 octane Unleaded

[Cotterik]

gas is airbound molecules, numbnuts.

[The_Canuck]

gas is airbound molecules, numbnuts.

Really!?! Shocking!

I also heard it's slang for gasoline.

[Cotterik]

orly!

[NSXType-R]

It's off topic, but will unleaded have a negative impact on older cars?

Sorry, I don't know enough to comment on this though.

[coolieman1220]

can u even get leaded gas?

[Ferrer]

It's off topic, but will unleaded have a negative impact on older cars?

Yes if they are not prepared to take on unleaded. Basically it's something to do with the weakness of the valves, but I'm sure that someone with a better knowledge of mechanical bits will be able to explain it better than I have.

[2ndclasscitizen]

It's off topic, but will unleaded have a negative impact on older cars?

If they are designed for leaded fuel, then yes, unleaded fuel will cause damage. In leaded fuel engines, the lead lubricates the valve seats. Since unleaded fuel can't do this, damage is done to the seats and valves. If you have the heads rebuilt and valve seats hardened this lubrication from the lead in the fuel isn't necessary.

[Bob]

Any car that runs unleaded gas will also run on leaded gas. The label that says "unleaded fuel only" on modern vehicles is ther because of environmental regulations, not mechanical restrictions.

[fpv_gtho]

I don't know whether or not the valve seat protector even works...I've never heard of it. To be safe, either pop the heads off and get the valve seats hardened, or use the leaded. You didn't get a car like this to be worried about pollution for sure.

Additionally, if you need higher octane, toluene can be bought in bulk much cheaper than octane boosters (which are themselves toluene). Just be careful that you get high quality stuff, you don't want contamination.

A few years ago when they took leaded fuel off the market here, they actually started to sell a lead replacement fuel, which was basically a pre-mixed premium with all the necessary additives.

[70cuda88]

hobbyshoppe, you seem to undoubtedly say unleaded, yet you vote leaded... hmmmmmmm

[adperrak]

Currently I am waiting for the car's tank to empty, in order to re-fill it with unleaded. Once I do so I'll be able to say the difference and eventually vote.

[revetec]

Any car that runs unleaded gas will also run on leaded gas. The label that says "unleaded fuel only" on modern vehicles is ther because of environmental regulations, not mechanical restrictions.

Leaded fuel will damage the Catalytic converter by coating the platinum which stops it from working.

Unleaded fuel in a leaded engine, really only cast iron heads without inserts and guides will be affected. If you replace the valve guides and seats to hardened ones, all will be ok. Most cylinder head shops can do this.

I ran unleaded fuel in my 1981 Holden Gemini for many years with no problems, which normally ran on leaded fuel. It had and alloy head, so naturally it had hardened valve guides and seat inserts.

Both fuels have the same potential energy and if the octane rating is the same, and the engine has hardened valve guides and seats then the outcome should be the same. Again note: If you put leaded fuel in an unleaded car, the catalytic converter will fail. Probably no performance change will occur, and maybe the converter may eventually block up (A big maybe)

[Bob]

Leaded fuel will damage the Catalytic converter by coating the platinum which stops it from working.

Unleaded fuel in a leaded engine, really only cast iron heads without inserts and guides will be affected. If you replace the valve guides and seats to hardened ones, all will be ok. Most cylinder head shops can do this.

I ran unleaded fuel in my 1981 Holden Gemini for many years with no problems, which normally ran on leaded fuel. It had and alloy head, so naturally it had hardened valve guides and seat inserts.

Both fuels have the same potential energy and if the octane rating is the same, and the engine has hardened valve guides and seats then the outcome should be the same. Again note: If you put leaded fuel in an unleaded car, the catalytic converter will fail. Probably no performance change will occur, and maybe the converter may eventually block up (A big maybe)

True I was thinking in terms of engine failure. But if you're running leaded fuel you don't care much about the environment anyway and hence no cat.

[revetec]

I think the point is that there is no point in running leaded fuel in an unleaded engine. One thing to note is that I have been talking to Castrol technical and they said that if you run AVGAS, the oil has to be different. They suggest Aviator SD100. It's all to do with the combustion deposits. There seems to be a lot of differences between 100 octane unleaded and AVGAS in fuel and lubricants required.