3 ms·

Can you explain what is bad about "cold starts after long periods of inactivity"? Or provide a reference? It sounds interesting, but I do not know enough about

• jaclaz 9y ago
  In a nutshell? It's complicated, but basically an oil has two main functions: 1) lubricate 2) circulate and take away all impurities and metal debris (which are then - as much as possible - filtered and absorbed by the filter and - at least the steel ones - by one or more magnets), i.e. to "clean" (continuously) So the oil has many components inside, some of which with different weight (i.e. that may tend to separate) some of them that may be affected by water (the air that inevitably enters the engine can condensate) some by the oxigen in the air itself (i.e. oxidate). Moreover some metal parts in the engine that are normally covered by a thin film of oil may well, after some longer period of inactivity "dry up" and thus develop some oxidation themselves or "run dry" thus creating more debris (that will be washed at next start and thus contaminate the oil). And then there is the temperature cycles, an oil needs to be fluid enough when very cold yet do not become too fluid when heated, which adds the need of more components that may suffer from these cycles. As an example in some industrial setups (think of static diesel electric generators) the oil in the engine is pre-heated electrically to keep it always from going under a given temperature. All in all keeping it continuously mixed/moved and within a given temperature range is "better" for the oil.