I have the same problem:
1. A detailed description of the issue. Please include any error codes here.
3rd Race and already 3rd gearbox. I just tried Vietnam and is degrading about 5% per lap, with no flashbacks. Bahrain was a new gearbox and 75% at the end of a 25% race, with 2-3 flashbacks.
2. What version of the game you are using (Shown on the start screen in the bottom left corner of the screen)
My Team, 22 race season, Honda engine, no durability upgrades as yet.
4. What are your replication numbers? M