Tetenal Protectan Spray, from the label on the can:
Propane 20-40% ,n-Butane > 60%

Sometimes I use gas intended for a blowtorch, from the label:
Propane 30% , Butane 70%.

The Propane and Butane mixture should be inert, Tetenal Protectan Spray has been used for very many years.