Car Mechanic Simulator 2021

Take a job for an old car with a large engine. (I took one for a 1965 Bolt Cape Mk4 that had a V8 1carb OHV engine)

Open the hood and focus on one of the engine covers. The engine covers on my engine had 10 screws split into two parallel lines. Make sure your engine cover has this setup. Exhaust manifolds way also work but they tend to have smaller screws and less of them from what I've seen.

Line up your cursor with a full line of screws and just hold in the button to unscrew them all rapidly. Now remount the engine cover and repeat.

I would recommend doing this on PC if you can because you only need the mouse to do every step. Listen to a podcast or something while you do this because this is the worst grind in the game imo.

Absolutely save this for very last because I got all the other achievements in this game and yet I was only at ~4000 unscrewed bolts.

The progress bar for this achievement might continuing only during Missions (story or side tasks)
Every time i renovate a barn find it doesnt. I checked the progress after every job and the progress bar did go further.
Maybe this would help someone.

Only posting this to say the achievement appears to be bugged. I've reached 14,000 bolts undone, and progress has been frozen at 98%