The transition towards electric mobility and shift away from CO2-emitting vehicles has raised questions on the classic car scene regarding future fuel supplies. AMAG Classic commissioned Empa, the Swiss Federal Laboratories for Materials Science and Technology, to conduct a scientific study with MOTOREX. The result is highly promising: in a nutshell, it can be scientifically proven that it will be possible to still run these cultural assets on wheels in future with no downsides, using CO2-neutral (bio-)synthetic fuel, also known as synfuel.

Bio-synthetic alternative petrol

The fuel in question is a bio-synthetic petrol made from renewable raw materials, such as plant waste. The alternative petrol came from P1 Performance Fuels GmbH of Berlin (Germany) and has an octane rating of 97.7 octane. Compared to conventional petrol from a filling station (98 octane), the only difference between the fuels in terms of composition is that the bio-synthetic fuel has triple the methyl tert-butyl ether (MTBE) content. MTBE is often added to fossil petrol to increase the octane rating and reduce knocking in petrol engines. This difference did not have a noticeable impact during driving.

Trial operation over around 3,000 km

MOTOREX supported the study as a specialist in lubrication technology. In a series of tests, a VW Golf 1 with a 1.5-litre 4-cylinder engine (1978) and two Chrysler Valiants with 3.7-litre 6-cylinder engines (1971) were driven for several thousand kilometres, the compatibility of engine components with synfuel was studied, the emissions and performance figures were compared against conventional 98-octane petrol, and multiple oil samples were analysed. The tests were conducted with MOTOREX TOPAZ SAE 20W/50 motor oil. This high-performance multigrade engine oil containing zinc is ideal for operating both engines. It has extremely low evaporation loss (Noack) and therefore low oil consumption, while also guaranteeing highly reliable lubrication and good wear protection. In addition, its behaviour is not influenced by the new type of fuel. Certain effects, such as acidification, are even ‘softened’ in the long term.

Focussing on the effects on the engine

As the materials in older types of engine can react sensitively to certain substances and the technology from back then is known for high levels of fuel condensation due to blow-by gases in the motor oil, the use of the bio-synthetic alternative petrol was similar to an engine stress test. What’s more, MTBE has better solubility than conventional petrol made from fossil raw materials. This means that MTBE could loosen residue in the engine or have a negative impact on materials. The aim was to investigate these effects. And to find out how much of an effect the use of the alternative fuel would have during operation and how quickly this would happen. The motor oil provides transparent information about this. Precise oil analyses comparing it against fresh oil in the MOTOREX lab indicated non-critical behaviour overall. Further investigations were only needed into the decrease in oil viscosity in both vehicles (ingress of fuel) and the strong rise in the iron/lead values in the Chrysler Valiant. The increased values were linked to the materials and model, and so were unrelated to the fuel. This was proven by tests with two Chrysler Valiants with an identical design, with one using 98-octane petrol and the other using the bio-synthetic alternative petrol.

No significant differences

Comparative measurements on Empa’s roller test benches found that there were no significant differences between the bio-synthetic fuel and the standard 98-octane petrol for either the emissions or the performance data. In addition, no unusual behaviour was found on any of the tested materials in direct contact with the bio-synthetic fuel.

In summary, the Empa study proves there are no risks in operating classic vehicles with suitable synfuels. It also opens up future possibilities for CO2-optimised travel with combustion engines. MOTOREX is part of the solution, with a broad range of specific motor oils for tomorrow’s driving. For its part, AMAG will start receiving the first solar fuel from Synhelion this year, for use in its classic cars.

The successful use of TOPAZ SAE 20W/50 with synthetic fuels also guarantees the high-quality standard for other TOPAZ viscosities. Other MOTOREX motor oils in conjunction with synfuels can also be used without any loss of performance.