Question: Engine lubrication

The Prius engine in normal driving is not off long enough for all the oil to drain, and the surfaces to loose lubrication. The engine is also warm. The wear occurs when starting a cold engine that has not had the oil flowing for hours, so there is not as much of a oil film left on the surfaces.

 

The Prius starts its engine differently than normal cars. The engine is spun up by a large electric motor (MG1) to a fairly good speed before gas and spark is applied. Only after the oil pressure comes up does the engine begin to fire.

Tom

 

Good point. I see a few PCrs have gone over 300,000 miles, so the engines seem to be very low wear.

 

The other factor is that the ICE is never subjected to rapid changes in torque. The Computers do very smooth changes (the cutoff of power when a wheel slips also protects the ICE). There are no rapid torque changes due to transmission shifting (eCVT) or user behavior.

My 2004 Prius is at 183,000 miles and it's ICE is doing fine.

JeffD

 

Isn't there always a thin film of oil on the surfaces that will never "drain" or dry out no matter how long the engine is stopped?

 

It wont go completely dry but the oil does gradually creep away.

To the OP. I thought the same thing when I first got the Prius, that all the stopping and starting of the engine must be bad for it, but now i think it's probably easier on the engine than most cars. The reasons are.

- Apart from the first one they're all warm starts with plenty of oil already in the bearings.

- As Qbee42 said, the Prius starts the engine in a different way to other cars, the engine is spun relatively quickly but at no load before fuel and ignition is applied. Even on the first cold start you're probably getting oil pressure before any load or ignition is applied.

- Also at cold starts the Prius really seems look after the engine by preferentially drawing power from the battery. This means that as long as you drive easy for the first minute or so then it just lets the engine warm up under almost no load.

Not surprisingly worn out engines are close to an unheard of problem around here.

 

Here's the only thing bad I've ever seen happen to the Prius Engine: