gas additive
Thread Starter
Racer
Joined: May 2010
Posts: 389
Likes: 10
From: madison ct
gas additive
I have an original 67' with the 350HP engine.I drive the car occasionally and don't beat on it. I have been adding lead additive to every tankful of gas for over 20 years. Is this necessary? I am being told that if you don't beat the engine the soft valve seats will be OK with unleaded gas? Don't want to ruin the heads. If I need to add the lead substitute can anyone reccomend one as my supply of additive has depleated over the years and I will need to purchase more.
CF Community Team
Joined: Oct 2004
Posts: 19,365
Likes: 5,244
From: Cape Cod, Mass.
2025 C6 of the Year Finalist - Unmodified
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
2021 C8 of the Year Finalist Unmodified
2020 Corvette of the Year Finalist (performance mods)
2019 C1 of Year Winner (performance mods)
2017 Corvette of the Year Finalist
2016 C2 of Year
2015 C3 of Year Finalist
You don't need it. I haven't used it on any of my old Corvettes and have never had any of the mythical valve recession problems. If anything, the plugs run much cleaner and longer without the lead.
Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
About the only gasoline additives I've seen worth using are gas dryer...the isopropyl alcohol type, to absorb moisture in the system; and fuel conditioner for when the car sits for long periods.
Any other additives are really unneeded as most oil companies put the necessary detergents, etc., in their additive packages. If a car needs more, then it has problems no over the counter additive will fix.
My Dad used to swear by Marvel Mystery Oil as an additive for gasoline and motor oil, but while I don't think it ever helped anything, I also don't believe it hurts anything either. Just unnecessary money spent.
Any other additives are really unneeded as most oil companies put the necessary detergents, etc., in their additive packages. If a car needs more, then it has problems no over the counter additive will fix.
My Dad used to swear by Marvel Mystery Oil as an additive for gasoline and motor oil, but while I don't think it ever helped anything, I also don't believe it hurts anything either. Just unnecessary money spent.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Melting Slicks
Joined: Dec 2008
Posts: 2,070
Likes: 5
From: N.Richland Hills Texas
On old round motors on planes "Marvel Mystery Oil" was a given to use... Airlines even added it to their DC-3's ect... Lot's of it still used... I've run it for years... "Light Plane Maintenance" ran test's on it some years ago... Same conclusion as mentioned above.... Could NOT see a positive but didn't hurt either.... (sounds like a goverment answer)
