Paul Marshall, a SCAPA member and owner of a 2000 Bonanza A36, has reported issues after using G100UL fuel for 67 hours. He published a report available here.
- From November 2, 2024, to March 9, 2025, the aircraft consumed 531 gallons of G100UL. The fuel was used for approximately 6700 statute miles, including four round trips to El Fuerte, Sinaloa, Mexico.
- The author experienced improved climb performance, reduced fuel burn, and lower metal wear based on oil analysis reports after using G100UL.
- The fuel caused paint significant and widespread damage, including staining and bubbling, potentially impacting the aircraft’s corrosion protection and airworthiness.
- Use of the fuel led to the presence of varnish deposits, rubbery substances, and increased friction on the oil dipstick, along with lower oil viscosity after short intervals, potentially impacting engine lubrication.
- A stronger fuel odor was initially noticed in the cabin after using G100UL, which was mitigated by airing out the cabin.
- Fiberglass fuel tanks, particularly tip tanks, are suspected of leaching substances into the G100UL, potentially causing deposits and impacting engine performance.
- A partially clogged fuel injector and unexplained black substance on the injectors were observed, raising concerns about potential fuel system degradation.
Michael Luvera, based at Reid Hillview (RHV) has, at the time of this post, published the results from a series of experiments in four parts: Part 1, Part 2, Part 3, Part 4. The results are shocking: in addition to the extremely toxic chemicals in the fuel, there are very serious materials and parts incompatibility. In addition to the report made by Paul Marshall, there have been numerous other reports around the Bay Area of severe damage caused to airplanes by this fuel.
Santa Clara County, as of the date of this post, has a 5,000 gallon tank full of this stuff just sitting at RHV. Sales of the fuel have dropped off to less than 100 gallons per week (you can only buy G100UL through full service at RHV). Despite all of the reported problems with this fuel, the County intends to keep selling it.
GAMI currently dismisses all these reported problems as “maintenance” issues. However, the brand reputation has been irreparably damaged. I will personally never use this fuel until some hard questions are answered.