I've asked people and gotten mixed answers. My friend google has given me basically the same results.

What say you? Should I buy lead additives for my original 69? It has had no engine work at all. I had the points distributor replaced recently. I changed the valve covers when the seal began leaking. Other than that, she's bone stock. I have used only 93 octane since I got it in 2001.

Here's a quote that says I don't need it.
"Extensive research and actual experience confirm that all cars – including older ones with soft valve seats – can operate on unleaded gasoline under normal driving conditions. Even in the case of engines subjected to high stress, such as in heavy duty farm equipment and motorcycles, unleaded gasoline has not caused significant engine damage. Valve seat recession is unlikely to occur except in extreme conditions – for example when vehicles are run constantly for days on end, and at high speeds, and carrying heavy loads."

 

My brother's vintage motorcycle recently destroyed the valves/seats. He was under the impression it was because he didn't use lead additives, which is what got me thinking about this.

 

ive never had a problem with running unleaded main things is haveing to run octane booster with some of the hotter motors.

if your 307 doesnt ping under load then u are fine running unleaded. if you start pumping up the comperession then you might have to add an octane booster.

 

He is talking about running unleaded gasoline in an old motor made for leaded gasoline without the hardened valve seats.

Ive always at least had a valve job to to put the hardened seats in.

 

Lead was an additive, and did help to prevent octane knock by giving the octane level a boost, as well as being a lubricant for the valves. Engines designed to run on unleaded gas have harder valve seats. The only way you'll know if using unleaded will have an adverse effect on your valves, is after it's too late. The answer, adding lead substitute to your gas tank.

 

i know what he was asking. ive never ever have had a problem with an older motor running on unleaded. ive seen older rubber in carbs have more issue with the ethenol in the gas than running unleaded

 

I appreciate the feedback. I think I'll add some lead every other tank or so just to be safe.

 

I've heard bad things about the additives as well. If additives are good, which are recommended? I've not seen real lead additives, just substitutes.