Engine break-in period?

Tthe position of the piston ring at the top of the stroke varies slightly with engine speed and load. If the engine is kept at constant speed ring wear will result in a small ridge in the cylinder at that point. Varying the engine speed spreads out that ridge so it is not a problem.

In the case of the Prius keeping the accelerator at constant position or the car at constant speed does not result in the engine being at constant speed as the system is constantly varying the engine speed to match the power requirements of the car. So it is less of a problem than a conventional car.

kevin

 

Kevin you said it's less of a problem than a conventional car. What is the problem

 

Very interesting. I was just looking at manual for 2023 and it references a break-in period of 600 miles/1000 km (as opposed to the 1000 miles/1600 km as prescribed for MY 2016).

The 2023 manual also makes mention of not driving “continuously in low gears” — hard to do with the e-CVT, unless I suppose you left the shifter in B mode…

 

meh.

Boilerplate.
They could have written that for a 1957 Ford F100.

Nice to see that there's no mention of checking the crankcase for metal shavings.

 

Varying the rpm means varying the load on the pistons is my take on it. Accelerate, then coast, then accelerate, loads the piston rings to the cylinder walls, then lets them cool, over and over. The loading is the breaking in. Pretty moderate to heavy accelerate then back off would be my view.