Amon won the pre-season Silverstone International Trophy, but once the F1 season began he found himself prevented from converting good qualifying positions into good results. He qualified second behind Stewart's Tyrrell-March for the season-opening South African Grand Prix only for his own March to overheat within fourteen laps. Amon then qualified sixth for the Spanish Grand Prix only for his March's Ford-Cosworth DFV engine to expire within ten laps. He qualified and ran second in the 1970 Monaco Grand Prix until his suspension failed twenty laps from the finish. This was the race where Amon refused to drive unless his entry number was changed from 18 – the number under which his then teammate Lorenzo Bandini had crashed and died in Monaco – to 28.