I'm asking in order to understand the risks (if any) specifically to an engine if I (cold) start it on days that are below 0f, and I don't use an oil pan heater or similar device.

If we need to be more specific, then for a reference point: speak about a typical inline 4 from the mid 2000s.

Also: what changes in this regard, when comparing full synthetic to conventional oil?

  • A search on here would get you this Q & A, which covers your question : mechanics.stackexchange.com/q/12688/10976
    – Solar Mike
    Feb 25, 2019 at 5:25
  • @SolarMike Your like gives an in-depth comparison between types of oils, but not what goes on inside an engine when it starts in sub-zero weather.
    – icor103
    Feb 25, 2019 at 5:29
  • It gets warmer... How's that. I expected that you would find the info useful as it would cover improving the starting between the oils, quicker warm-up, less wear etc....
    – Solar Mike
    Feb 25, 2019 at 5:31

1 Answer 1


During an extreme cold start, such as 0 degrees fahrenheit, -18 Celsius, conventional oil is the same as it would be in a glass jar in your freezer. You can test the difference in synthetic versus conventional oil in household freezer. Mobil-1 is the best, 0-20w

The pistons are tighter in the cylinder bores when cold, the rings are frozen in place on the pistons and may not seal for a minute or two. The oil will be heated very quickly right at the pump, but there will be no real oil flow for at least a minute or two, and this is when ALL engine damage occurs, not on the highway, and not at engine operating temperature, almost no wear occurs then. Winter Time, use Mobil-1 0-20w, or the smallest first number, of synthetic oil.

All oil comes from the same place, natural and synthetic comes from crude oil. The difference is the additives, from all sorts of things, including other pretroleum distillates. Here is a list of things they add.

Detergent additives, - Typical detergents are magnesium sulfonates. Corrosion or rust inhibiting additives retard oxidation of metals. Antioxidant additives retards oil degradation using organic amines and phenols. Metal deactivators , such as phosphoric acid. Bases , neutralize all sorts of acids. Alkaline additives are used to neutralize the acids mentioned previously and include magnesium and calcium sulphonates, salicylates, and phenates.[4] urement of a motor oil's degradation and longevity is its TBN relative to a new oil. Viscosity modifiers make an oil's viscosity higher at elevated temperatures Friction modifiers or friction reducers, like molybdenum disulfide. Nanoparticle flakes from the oil additive TriboTEX. Image taken with electron Antiwear additives or wear inhibiting additives such as ZINC.....RE: high ZINC oil Anti-foam agents (defoamants) inhibit the production of air bubbles and foam Antimisting agents prevent the atomization of the oil. Wax crystal modifiers are dewaxing aids that improve the ability of oil filters to separate wax from oil.

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