Do the majority of older cars (pre-1980) require leaded gasoline (or a lead additive) or can you go ahead and pump unleaded into the tank without fear of any consequences?
“My hovercraft is full of eels.”
They year is '73 or thereabouts, and you need to add a lead substitute
I’ve got a 63 Corvair. For the last couple of years I’ve used the high octane stuff, and it runs fine.
Billehunt:
(please, not again)
Is it the original engine? has it been modified to accept unleaded? If not, the engine needs the lead or the substitute for lubrication. If you are not using it, you are damaging the engine.
Lawnmowers, old vw’s, etc do fine on unleaded. You don’t have to add lead substitute at all unless you go 60mph a lot.
the lead cushions and lubricates the valves in older engines. If it doesn’t say “unleaded fuel only” and hasn’t been rebuilt with hardened valve seats, then you need to use a lead substitute.
Yes, lead did help lubricate the valve guides and seats, and yes, running one of these older motors without leaded gas will cause those areas to wear faster, but an additive is not neccesary.
It will take about 50k miles of normal driving to see any significant wear due to the lack of lead in the gas. At that time you can replace the guides and seats for far less than what you would have spent on additives.
I would only recommend an additive if you car knocks with premium unleaded AND you have already tried all the normal tricks (re-curve the dist, thicker head gaskets, etc).
‘the lead cushions and lubricates the valves in older engines. If it doesn’t say “unleaded
fuel only” and hasn’t been rebuilt with hardened valve seats, then you need to use a
lead substitute.’
This is a common misperception & has been proven to not be the case by the biggest automotive people in the world.
As I recall, lead was added to gasoline as an Octane enhancer. I will try to get references when I have time. The biggest problem with unleaded was that the octane ratings were low. The main thing to do is to retard the engine timing so that the lower octane gas have time to complete is combustion before the piston hits TDC. The flame front is much slower. Otherwise severe knocking will occur. The same thing will happen if you put low octane gas into a high compression high performance engine. But because you retard the timing, an old engine will produce much less horsepower, but its workable.