Motor Oil And Cold Temperatures

The term “Cold” can be relative.  It all depends on what you are used to. In the summer, 50 degrees can feel cold yet, in the middle of winter, it can feel downright balmy.  For this post however, we’re talking about motor oil and for motor oil, cold temperatures below 40 degrees will have a negative effect on the oils flow characteristics.

If you have ever tried pouring a quart of oil out of a bottle that has been stored in a 30 degree trunk or garage you know how long it takes to drain the bottle.  I haven’t ever timed it but my guess is that it takes at least 2 to 3 times longer to drain than if it was stored at 70 degrees.  Now how about in a freezer at 0 degrees for 12 hours. Does the phrase “Slower Than Cold Molasses” come to mind?

Now think about how this thicker oil effects your engine.

  • The extra drag created by the thicker oil slows your engines cranking speed, puts extra strain on your battery and starter and makes it harder for your engine to turn over and start.
  • Once started, the thicker oil is hard to pump, doesn’t readily flow through the oil filter but activates the by-pass valve, letting unfiltered oil provide the lubrication. It is also putting additional strain on the oil pump and the components that drive it.
  • If cold enough, even though it is flowing, it may be too thick to flow readily into tight clearances leaving components starved for oil and causing excess wear. If there are any parts that require “Splash” lubrication, they’re not getting lubricated.
  • Thick, heavy oil reduces fuel economy.

So, what can you do to minimize these problems?  First, look at the specifications for your oil.  The “Pour Point” will tell you the temperature at which the oil just barely pours. (Borderline Pumping Temperature is actually a better number but most manufacturers don’t publish it.  If you add 10 to 15 degrees to the Pour Point you should be close to the BPT, the minimum temperature at which your oil will pump.)  Second, look at the Cold Crank Simulator Viscosity. (CCS Viscosity)  The readings are in centipoise which is more technical than most people want to get but the result of the test is a measure of the resistance of a shaft spinning in the cold oil and can be used to compare oils.  The lower the number, the lower the resistance, the easier the oil pumps and the easier your engine starts.  Keep in mind that the test is done at a specific temperature depending on the viscosity so just be sure when comparing that the oils are the same viscosity.

So if you want your car to start easier in the winter and give you better fuel economy, use a quality synthetic oil like AMSOIL.  Your engine will thank you for it.

The following list gives you the Viscosity, Pour Point, CCS Viscosity of AMSOIL Signature Series Oils and the Maximum Allowed by the CCS Viscosity Standard for any oil of that viscosity.

Viscosity        Pour Point   AMSOIL      Max Allowed

  • ASM 0w20      -63F              4979            6200 @ -35C
  • ALM 5w20      -63F              4210            6600 @ -30C
  • AZO 0w30     -60F               5909            6200 @ -35C
  • ASL 5w30     -60F                4426            6600 @ -30C
  • ATM 10w30   -54F               3646            7000 @ -25C

Since most petroleum oils and even some synthetics will be in the -25F to -35F Pour Point range, their BPT will be in the -10F to -20F range.  While we don’t normally get down to those temperatures here in southern New England, they are not that unusual if you head north in the winter for some skiing, snowmobiling, snowshoeing etc.  So do your vehicles and yourself a favor.  Keep them filled with a quality synthetic like AMSOIL and if you have to start after a night of -30F temperatures, you won’t have to worry that the oil isn’t doing its job.  (And, it may make the difference between starting and not starting.)

Now Check Out Your Oil And See How It Compares.

SAE J300 Standard – Cold Crank Viscosity Max Limits

Viscosity                          (mPa’s) Max (CCS)

  • 0W                               6200 @ -35° C
  • 5W                               6600 @ -30° C
  • 10W                             7000 @ -25° C
  • 15W                             7000 @ -20° C
  • 20W                            9500 @ -15° C
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