[Drivingforfun]

I'm aware of the facts that no fuel is used when driving downhill without accelerating, and of low gears tending to be encouraged, but I often drive down minor hills which are steep enough to not require acceleration but not severe enough to need any braking (whether engine- or foot brake)

Would putting the car in a higher gear in these scenarios be beneficial in reducing wear?? If the engine is spinning at a given RPM then surely something is moving - and so wearing - even if no fuel is being pumped into the engine?

Thanks

[Rolebama]

Wear is a lot less on the overrun as there is no nasty combustion taking place. I would guess that the overall effect of wear difference depending on what gear you are in would be negligible. The gearbox wear would be reduced in the direct drive ratio, as the majority of spinny bits in the gearbox would be taking no strain.

[olduser]

Under ideal conditions any wearing surfaces have a finite life, industrial bearing manufactures usually express the anticipated life of bearings in number of revolutions under ideal load conditions.
In IC engines most of the bearings loads are far from ideal, thrust from compression, combustion, out of balances forces, changes in temperature all add up to a tough life.
So it is true to say they will have a finite number of revolutions, shortened by any abuse.

Changing down the gears to generate a retarding force dates from the days when brakes were not very good.
From the same time drivers used the gearbox when coming to a halt, going down through all the gears in turn.
But with modern brakes being much more easily able to dissipate heat using the brakes would seem to be the better option.
On the grounds it is much cheaper to replace brakes than it is clutches and gears, it would appear to be better to use the brakes.
Having said that, I am from the generation when brakes easily overheated, when you have experienced brake fade you never want to experience again!
Which means I still use some engine braking on long descents but with the major braking coming from the brakes.
With 5 speed gearbox I would use 4th where on engine only I may have had to use 3rd or even 2nd.

I think, I was taught (or it may be a habit) to use the highest gear the engine is comfortable with for normal driving.
If acceleration is wanted, then lower gears are needed but as soon as acceleration is over it's back to the highest gear.

[NMNeil]

Originally Posted by olduser

If acceleration is wanted, then lower gears are needed but as soon as acceleration is over it's back to the highest gear.

I wonder if they will ever develop a gearbox that will do that automatically?
Couldn't resist😁