Overview
- From 1 June the FIA amended Article C5.4.3 so engines must comply with the 16:1 compression limit both when cold and when measured at an oil temperature of 130°C.
- The revised wording also bans any component or system designed to raise compression under running conditions and commits to using operating-temperature checks only from 2027.
- Paddock reports had suggested Mercedes’ power unit could pass cold checks yet run higher effective compression at race temperature, but all Mercedes units previously passed the FIA’s inspections under the old procedure.
- It is unclear whether the change will cut on-track performance because teams can adjust hardware or fuel during scheduled power-unit rotations and any required fixes can be fitted as engines are replaced.
- McLaren is marking its 1,000th Grand Prix in Monaco with a special metallic papaya livery and a grid display of its original M2B, while team principal Andrea Stella says the team’s start to 2026 has been challenging and below expectations.