As explained here (Is it true that most of the engine wear during its life time occurs during a cold start up?) most of the wear of an engine is during startup and especially during cold startup. Why don't engines implement an automated procedure to (electrically per say) operate for a few of revs without ignition and compression, and at the same time pump oil so everything is oiled up properly and THEN ignite and start normal operation???

  • I could ask why put all that effort into making the engine last longer, when most cars probably go to the breakers with a good fully working engine in them. – HandyHowie Nov 21 '18 at 8:09
  • Well we could also ask why to make a car last longer in general as an opposition to basic capitalism principles... But i thing this is "engine-theory" for. – kokobill Nov 21 '18 at 8:27

The main reason oil does not circulate very well at startup is because the oil is at a low temperature. It takes a minimal amount of time for the oil to reach pressure when the engine first starts but it takes around 10 minutes for the oil to warm up to the point where it's at it's optimum temperature and able to get around the whole of the engine.

So, in order to ensure that the oil was providing effective protection at startup, you'd have to pre-heat the oil for some time before setting off. There are technologies such as "block heaters" by firms such as Kenlowe that can do this. They typically rely on a mains power cable and you switch them on half an hour or so before setting off.

Most manufacturers won't provide this technology on their vehicles because most consumers don't want to wait half an hour before driving off just to counter minimal engine ware due to cold oil.

  • However, you can install a block heater as an aftermarket item. Actually, on my 2016 RAV4 hybrid, the block heater is integrated with the cooling system on the vehicle, even using a coolant pump... – juhist Dec 21 '18 at 17:42

Some vehicles locked out the ignition until sufficient oil pressure had been built-up...

Systems to do this exist and are beneficial, but the cost, at the manufacturing point, makes it too expensive, both due to the amount of benefit and accountants that limit the value that can be put into a car. The car is built to meet a price-point for the market and the costs are kept below that.


This actually illustrates why hybrid electric vehicles are good.

The most wear occurs due to forces caused by combustion in the cylinder. No combustion, not much extra wear.

So, to start up an engine without much extra wear, you want to:

  1. Spin the engine to its operating idle RPM
  2. Wait few seconds for oil to circulate
  3. Start to inject fuel so that the engine runs on its own power and not on electrical power, only after oil has had a chance to circulate

Now, why aren't all cars started this way? The reason is that the lead-acid battery is very small, so you want to limit the amount of time the engine runs on electrical power. The feeble starter motor can't quite spin the engine to its idle RPM, just enough that the combustion can supply the extra power to reach idle RPM.

A conventional car is started in this way:

  1. Spin the engine to not quite its idle RPM
  2. Inject fuel immediately
  3. Let the injected fuel provide the extra boost immediately, before oil has had a chance to circulate

However, on hybrid electric vehicles, there is ample energy in the battery and the large motor-generators can actually spin the engine at its idle RPM for many, many seconds (or minutes!). Thus, it's possible to have oil circulation before combustion.

I'd bet an engine in a hybrid electric vehicle far outlasts an engine in a conventional car due to lower startup wear.

However, there is still the problem of oil temperature. A hybrid electric vehicle helps here as well: it's possible to operate the engine at a lower power point, supplying the extra needed energy from the battery, until the oil is warm.

  • The reason wear happens is because oil is cold. Running the engine will warm the oil but cause wear during warmup. This is true irresponsible of the type of engine or application. Running at low loads prolongs the time taken to bring the oil up to temperature. – Steve Matthews Dec 23 '18 at 18:36

Every mechanic knows the two factors that contribute the most to wear is HEAT and FRICTION. A pre-oiler will double or triple engine life.....and they are cheaper than repairs down the road.

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