My personal experience with a 58 Chevy with the original I6 is that the lead additive is not needed. Admittedly, I only drive it occasionally now, but I stopped bothering with lead additive shortly after I started. At that time it was my daily driver, and I put about 15k miles on it in a little over a year without lead in the gas and without any engine problems. I have since put another 4K-5K miles on it in the last ten years with no engine problems.

 

If you don't run your engine hard, you don't need to worry about the lead additive.

 

look do us all a favor and put it in every other tank then you should be ok cause its not like you have cats to screw up and you don't know bout your valve seats so its a win win situation

 

I don't believe any lead additive is needed.When lead was removed from gas years back,there was lots of confusion about installing new valve seats on older engines.But like another post just replied,the gasoline we use today has other substitutes that equal or better the lead gasoline.So no need for any additives.

 

A lot of good information in all these posts. If I could summarize it, it goes something like this:

Tetra-Ethyl Lead was added to fuel to increase the Octane rating (that's where the name "Ethyl" came from). It didn't take long before the lead would coat the valve seats forming a cushon that the valve would seat against (it actually permiates the soft metal valve seats). This also meant that the factories didn't need to install the more expensive hardened seats.
Unless the valve seats have been cut, there is no reason to continue to run an additive. If you have the heads serviced you will want to change to Hardened valve seats.
There used to be an add in the back of the magazines where a guy said he had "old stock Tetra-Ethyl lead additive". Might still be there, I haven't looked. Frankly I'm not so sure it wasn't snake oil. That's about the only way, short of running leaded race fuel you are going to find true "lead additive". Stop and think about it. If you were really adding lead, you'd be increasing your Octane, and it would hurt your performance unless you made adjustments.
We quit putting it in fuel because we thought it was causing brain damage in children. Little did we know at the time, it was just the "dumming down of America"
My '66 (6 cylinder) still has the original headgasket. I'm not running any lead in it (save for my right foot). Nor have I run any lead in the other old cars I've restored.
However, like the hippies said in the '60s..."if it feels good, do it". It's cheap, and won't hurt anything, as long as it's a legal additive. Hell, we're filling our water with MTBEs now anyways. Still haven't seen any kids with 3 eyes or two noses... or a decent SAT score.

 

There seems to be a general thought, that once the valve seats get coated with lead, then they are good to go for the rest of the life of the engine, and no further lead additive cushioning has to take place. Yes, lead was used to increase octane back in the early days when gas was rated at 60 octane, and could not be burned in engines without an increase to at least 87 octane. But, the second effect was to cushion the soft valve seats. I believe the lead that was used in my 289 has long since been burned off, and that my soft valve seats need some cushioning. That is why I still use a lead substitute. Just don't believe that a lead substiture is lead. It is not. It is a substitute. My car doesn't ping using 87 octane gas, and my valves are in great condition. Believe what you want, and either use it or not.

 

lead substitutes just gum thing up i wouldnt use them

 

Do you have personal experience with that? I do, and it certainly does not gum up my engine.