Has anyone told you lately that you really need to think about getting your hands on a lead substitute? If so, the chances are pretty good that you’re a dedicated classic car enthusiast, and if you don’t already drive a classic car, then you’re likely thinking about getting one soon.

However, hearing about lead fuel additive is one thing. Knowing what it is and understanding what it can do for your classic is another. So, what is lead substitute anyway? Is it something that’s truly necessary, something that’s simply nice to have, or just one of those things that really isn’t all that important at all?

Why Might a Classic Car Need a Lead Substitute?

Classic cars are more than just beautiful reminders of bygone eras. They are relics of those eras, so when people say they don’t build them like they used to anymore, they’re more correct than they probably realize. For one thing, bona fide classics were manufactured during a time when gasoline still came with lead in it. That lead served several functions as far as how it helped a car run. Lead additive does the same now that lead has been banned. Among other things, lead:

  • Helped reduce knocking.
  • Made higher compression ratios possible by raising fuel octane ratings.
  • Minimized wear and tear on the car’s valve seats by lowering the likelihood of microwelds.

What are microwelds? They’re bonds that can occur between the cylinder head and the valve seats once the engine gets hot enough. Naturally, once a microweld occurs, it also needs to be pulled free again once the valve reopens. Over time, this process can be pretty hard on the valve seats involved, and repairing them was typically very expensive.

That hasn’t exactly changed over time either, so most classic car owners are very invested in preventing valve seat wear and tear to the greatest extent possible. As you’re likely very aware, gasoline is no longer made with lead because of how highly toxic it is, so lead fuel additive options were developed as a way to make up the difference.

How Long Has Leaded Fuel Been Off the Market?

People first began to understand just how toxic lead really was at some point during the mid-70’s. In addition to the health and environmental hazards it posed, it was also found that lead didn’t gel well at all with catalytic converters and could drastically affect their function. The state of California was the first to officially decide leaded fuel was a no-go back in 1992, and once that happened, it didn’t take long at all for the rest of the country to follow in its footsteps.

Of course, the way car engines were made had to change as well. That happened in the form of valve seats that were much harder, more durable, and better able to resist the effects of the high temperatures responsible for the formation of microwelds. Unleaded gasoline no longer posed a threat to engines at all once those standards became mainstream (unless the engines in question were older, of course). Modern lead substitutes were introduced to make up the difference for older vehicles still on the road.

Although the exact formula of a lead substitute is going to vary from product to product, most are based on a cocktail of different metallic elements. These include but are not necessarily limited to iron, manganese, and sodium. Although these newer formulas are capable of playing the same role lead used to when it comes to older engines and vehicles, they are not harmful to catalytic converters or considered toxic in any way.

Is It Still Possible To Buy Leaded Fuel?

Of course, you may simply be asking: “Where can I buy leaded gas?” After all the real thing has got to be better for your classic car than a substitute, right? To answer that question: you’re not going to be able to roll up to a gas station and buy leaded gas anymore. Technically speaking, it does still exist and is permitted in specific types of vehicles (like aircraft or farm vehicles, to name two examples). It’s no longer legal to put leaded gas in your car though, whether it’s a classic or not.

Don’t even think about trying to do it on the downlow either. If you’re found to be driving a car with leaded gas in the tank, you could well wind up slapped with a hefty $10,000 fine for your ingenuity. In other words, lead substitute is really the only acceptable alternative.

Do You Need It?

Whether or not you’d really benefit from adding a lead fuel additive to your repertoire depends on the current state of your car’s engine. Obviously, if your classic car’s engine has been refurbished to meet modern standards, you really don’t need the additive. In fact, even if the engine is older, you may be able get by without it.

There are plenty of older car engines out there that contain hard enough valve seats that microwelds really aren’t a problem, especially those that came out in the mid-60’s or later. Upgrading your fuel to a high-performance option is often recommended by serious classic auto experts, but you’re probably fine without the actual substitute, especially if your vehicle has been running fine without it for quite some time already.

There are still circumstances under which you might do better with a lead substitute than without one though. If your classic car is still equipped with its original engine, it’s not going to hurt you to factor in an fuel additive. It will certainly reduce any potential hazards posed by modern unleaded fuel if you’re worried and want to make sure all your bases are covered. Just take care that the associated octane levels are properly aligned with your car’s needs and you’re good to go.

In conclusion, if you’re really passionate about classic cars, lead fuel additive is definitely a good thing to know about and consider. It probably isn’t essential for most vehicles, but it definitely isn’t going to do any harm and can help some older vehicles run more smoothly. Ultimately, it’s up to you.

Advice, how-to guides, and car care information featured on and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

FREE Loan-A-Tool® program requires returnable deposit. Please note that the tool that you receive after placing an online order may be in a used but operable condition due to the nature of the Loan-A-Tool® program.

Related Posts