Sta-Bil + Lead Substitute + Marvel Mystery Oil = Too many additives?

I own a '64 Chevy. It gets about 300 miles/year. I also live in an area where ethanol-free gas is hard to come by, so Stabil is a must.

I have been thinking about also adding lead substitute and marvel mystery oil to each tank. But I’m thinking… that’s a lot of additives. Is it too much? Might they react and cause problems? If so, which ones should I add and which ones should I drop?

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@jeepsurf22 - Out of curiosity, why do you add lead substitute? I guess I would be interested to hear why you would like to add the lead and Marvel Mystery oil.

I use StaBil and nothing else on my '65 Corvair, but I drive a little more than you do each year.

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Full disclosure I have no technical background, but understand that lead was the original octane booster as well as a way to cushion unhardened valve seats. I’m not sure when Chevrolet started using hardened valve seats…I want to say it wasn’t until the late 60’s. If that’s right, and your engine is a high-compression version AND has never been opened and hardened seats used, it MIGHT not be a bad thing to use a lead additive. And no more miles you put on it, the extra cost would be negligible. If it has had hardened seats added (like many by now probably have) and you don’t have a problem with knock or ping, I’d think you’d be fine just running a good non-ethanol 91 or so in it.
Off-hand, I can’t think of any harm MMO would do. But in my experience it’s as much a solvent as oil. I’ve heard it may have some small effect at reducing carbon deposits, but with modern fuels, modern oil and with prudent change intervals, I’m not sure of the benefit.
At only 300 miles a year, I’d keep the fuel stabilizer even with non-ethanol.

FWIW, I haven’t used anything in my '54 235 over the past 35+ years and maybe 35k miles since it’s rebuild (with hardened seats) except ethanol-free fuel when I can get it…which is 89 or better where I live. And at the factory timing settings, that’s plenty high octane for the old girl.

I use lead substitute because my classic is an all-original 1963 chevy that has never had hardened valve seats swapped in.

I have a 69 Grand Prix which comes from the factory without hardened exhaust seats as well. @Jim-R to my understanding, anything from GM built before 72 should not have hardened seats. I cannot speak for the other companies, but I would assume the same for them.

The following is an opinion and should be taken as such. I look at most fuel additives as snake oil or placebos. This is an opinion formed from spending a few years slinging car parts at the local NAPA. I do believe that Sta-Bil and some fuel system cleaners work, my preference being Seafoam because it does a good job as both a cleaner and stabilizer. I do not run lead substitute in my Pontiac, because I’m not really convinced that it carries enough lubricating properties to sufficiently replace the properties of real lead in gasoline.

I do drive my car more than you do from the sounds of it, but if I did not have access to non-ethanol fuel, I would do what @Kyle does with his Corvair and run Sta-Bil. Or I’d substitute with Seafoam if you wanted to have a fuel system cleaner for good measure.

Apparently it’s working for you. But I don’t think the lead back in the day, nor the lead substitute of today is intended to have lubricating qualities. Just a sacrificial metal on the valve seats to prevent pitting over time… and an octane booster.

Probably a better description of what it does. Granted, I’ve never pulled the heads off of my car, but it runs very well.