Should You Use Lead-Reducing Fuel Additives?

A FLYING reader asks our A&P author if using these fuel treatments will help their aircraft.

Richard Scarbrough

Wednesday, June 22, 2022 at 08:31 AM ET

Verified

An Aeronca 7AC Champ aircraft. [FLYING Archive]

Key Takeaways:

Lead from 100LL avgas is a harmful element that causes engine deposits, with unleaded fuel alternatives showing significantly cleaner results.
Additives like TCP (tricresyl phosphate) are effective tetraethyl lead (TEL) scavengers designed to reduce lead deposits and prevent plug fouling.
Using lead-reducing additives is recommended as a preventative measure to mitigate lead's effects, even if no current fouling issues are observed, until more inclusive unleaded avgas approvals are widespread.
When choosing fuel additives, prioritize FAA approval, though specific products like Alcor's TCP are already rated for many powerplants without needing additional approvals.

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Q: I fly a Champ with a Continental C-85 engine, and I am confused about the benefits of fuel treatments like TCP that reduce lead deposits from 100LL. My spark plugs look clean. Is it just a good idea to use lead-reducing fuel additives anyway?

A: There is no secret about the harmful effects of lead. I recently spoke with George Braly of General Aviation Modifications Inc. (GAMI), who is currently running tests for their unleaded avgas alternative G100UL. Initial teardowns of the tested powerplant showed cleanliness far superior to that of leaded 100LL. Lead is a dirty business, a foul element (no pun intended), and better left to history.

Aircraft Spruce & Specialty carries a wide range of lead-reducing additives, including TCP. While we cannot review each one individually, one key indicator to look for when choosing an aircraft product is FAA approval. It is always a good idea to stay in line with the feds.