Should I Use a Lighter Viscosity Oil in Winter?

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Do I need to use a lighter viscosity oil in my car during the cold winter months?

As an AMSOIL Dealer, I get this a lot, especially in as the days get colder. The short answer is

Yes – if your manufacturer allows it.

Check in your glove box and see if what your owners manual says. In the back is usually where you find the oil recommendations.

For most vehicles, it will be 5W-20 or 5W-30. Typically, it doesn’t matter if it is -30ºF or 120ºF, modern engings are designed to be most fuel efficient using that viscosity of motor oil.

Some cars and heavy-duty equipment recommend a different viscosity depending on the outside air temperature. You might see a chart in your owners manual like this one below that shows different oil viscosity recommendations based on how hot or cold it is. Usually a lighter viscosity oil is to be used as it gets colder, during the winter.

amsoil full synthetic



If that is the case, use the lightest recommended viscosity during the cold winter months.


Two reasons:

  • To ensure your car gets maximum wear protection during startup
  • To make sure you have easier cold weather start-ups


If you need a refresher about what viscosity is, ==> Check out this post for a detailed explanation of viscosity

In a nut shell, viscosity refers to a motor oil;s resistance to flow, and it is usually considered its most important attribute. The lower the viscosity, the easier it flows in colder temperatures. On the opposite side, the higher the viscosity of a motor oil the slower it will flow when it is cold. So an 0W-20 oil will flow easier when it is cold, compared to an oil with a viscosity 10W-30.

Explain Oil Number Meaning

What do oil numbers mean? The oil viscosity numbers are simple.

The first number, followed by a W describes the characteristics of the oil when it is cold. In this case, cold is 104ºF. The second number, describes that oils characteristics once that engine heats up, which is 212ºF.

Most of the engine wear happens when you start your engine. Why? Because a lot of the oil is drawn into the sump of your vehicle as it sits still. When you start your engine up in the morning, even if it isn’t’ that cold, a few seconds pass until the oil gets through your oil pump and finds it way to the components of your engine. THAT IS WHEN YOUR ENGINE WEAR TAKES PLACE.

That is why it is a big benefit to your engine to use an oil that flows easily during startup. Oil that flows easily will get to your engine faster, and more efficiently.

Lower viscosity oil, will get there faster, and allow better cold weather startup, when compared to higher viscosity motor oils.

Crank it up

Another benefit of low viscosity oil is that they provide less crankshaft resistance when your engine turns over. This is especially important as the weather gets below zero. The oil gets so thick that it can prevent the crankshaft from rolling over fast enough to get your engine to start.

If you are using conventional oil, they my contain waxes, which will further thicken when it is cold. Full synthetic AMSOIL motor oil does not contain these thick waxes, which is why it is the best oil for cold weather.

Check out the video for proof.

AMSOIL Tech Tips: Maximum Start-up Protection


Another benefit that you will see from lower viscosity oil is better fuel economy. You may have noticed that more automakers are recommending a lighter viscosity oil in newer vehicles.

Do Higher Viscosity Oils Have Any Benefits?

With all this talk of lower viscosity oil, you may be wondering if there are any benefits to higher viscosity oils.

Oils with higher viscosity tend to give your better protection against wear. They give your engine a thicker film on your engines parts. They also tend to be more resistant to oil consumption compared to lighter viscosity motor oil.

Bottom Line: If you live in a part of the world that gets cold in the winter, you should switch to the lightest viscosity oil that your manufacturer recommends. You will maximize your engines wear protection during cold weather startups.

amsoil full synthetic

Jim Underwood


  1. I have a 2004 Silverado, and I have used AMSOIL Signature Series 5W30 since I’ve bought it brand new. Runs as good now as the first day I bought it, maybe even better!

    I buy 6 quarts and a filter, get free shipping on AMSOIL products, and my order arrives in a day or two. AMSOIL is the best motor oil, PERIOD. Mobil 1 and Royal Purple can’t compare to full synthetic AMSOIL.  I use AMSOIL products in my truck, my motorcycle, and my ATV.

    Once a year or every 25,000 miles, and I’m protected.

  2. I use full synthetic AMSOIL in my 2014 Chevy Silverado.  Nothing but good things to say about AMSOIL.  With the discount and the convenience of getting it delivered, why would I use anything else?  

    I have no problems with cold starts, and I get better MPG with AMSOIL.  

    I really like that there is a company that manufactures oil in the USA, and they provide routine discounts through Best-Synthetic-Oil-USA.com

  3. I have been using AMSOIL products for a while now, mosty in my dirtbikes and pickup truck. I want to start selling, because a lot of my friends and family also use AMSOIL products.

    My question is, since I own a lawn and garden supply store, can I sell AMSOIL products for profit?  Is that something you can help me out with setting up? 

    • Sure, you will want to fill out  AMSOIL RETAIL ACCOUNT” target=”_blank”>==> AMSOIL RETAIL ACCOUNT application. This is for  

      Auto parts, farm supply, lawn & garden, convenience, hardware and other retail storesMotorcycle, marine, ATV/UTV, snowmobile and other powersports dealersFull-service garage, heavy-duty truck repair, quick lube, auto dealer and other service shops

      I will be more than happy to help you get set up. I think you will find that selling AMSOIL products is a great way to get more customers in your store.

  4. Living in northern Minnesota we know what a cold winter feels like.  Last year we switched to full synthetic  AMSOIL for our 2012 Camry and 2010 Chevy Silverado. I could really tell that my Camry was started much easier, even during the record breaking cold.

    This summer I noticed an increase in the MPG I was getting, and I know my husband likes the extended old change of 25,000 miles.

    We just ordered more AMSOIL Signature Series Full Synthetic motor oil for our car and truck, plus are switching to AMSOIL for our ATV’s and my Harley!  I’m sold!.


    • Thanks Babs, I’m glad you were able to use your reward points to get an even bigger discount!

    • Hey Darren,  

      I can certainly cut you a break.    Send me an email jim@best-synthetic-oil-usa.com, and I will send you a quote. I can give you a 25% off retail, and ship it for free. 

      I always offer discounts that AMSOIL doesn’t want me to advertise, they want to protect their other dealers, and I respect that.  

  5. My eldest son has been using various AMSOIL products on his off road bike over the last five years or so, especially in the cold weather. He frequently takes part in off road races around our forestry areas but has had the last several months off due to injury. 

    If I was to look into purchasing a few AMSOIL products for him for Christmas, where would be the cheapest and best value place to buy online, in your recommendation?

  6. Great insights Jim. I had no idea whatsoever that oil viscosity matters for my car depending on the climate, whether cold or not. I will countercheck manufacturer recommendations for the best viscosity I need to use in my car when winter comes. I really appreciate the information, many thanks.

    I will yearn to maximise the friction protection during adverse conditions.

    Best regards

  7. An excellent explanation for the use of car oil. I have a Volvo XC70 with a diesel engine and I use either 5W-30 or 0W-30 which is more expensive. The only thing I don’t understand is why the 0W-30 manufacturer recommends changing oil every 30K km, but the service staff every 15-20K km?

  8. I live in a warmer climate where the temperature very seldom drops below 0C / 32F and even when it does it  typically doesn’t stay there for more than an hour or two. But I have been using full synthetic AMSOIL in my truck and all of my motorcycles.  Nothing else performs, and AMSOIL  saves me time and money.

  9. When I lived in the UK, AMSOIL oil was difficult to get hold of due to a small dealer network. Even so I was able to get hold of the synthetic oil.  My 10 year old Ford Focus started every time and was problem free for years.

    Since then, I moved to The Netherlands and I haven’t been able to get hold of it again.

    As a dealer, are you able to assist me in finding a source for The Netherlands? 

    I prefer AMSOIL to any other brand.

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