Engine oil begins to thicken at temperatures between -14°F and -58°F (-10°C to -50°C), depending on its type and viscosity.
Let’s look at the warning signs that your oil has thickened, key factors that influence its freezing point, and tips to prevent this from happening.
This Article Contains:
- What Temperature Does Engine Oil Freeze?
- 4 Warning Signs Your Engine Oil Has Thickened
- 4 Factors Influencing the Freezing Point of Engine Oil (+ What to Do)
- How Do You Handle Thickened Motor Oil? (Especially if You Park Outside in the Cold)
What Temperature Does Engine Oil Freeze?
Depending on their formulation and viscosity grade (a measure of oil thickness and flow), most oils begin to thicken when temperatures reach -14°F to -58°F (-10°C and -50°C).
Conventional oils typically become sluggish at the higher end of this range, while synthetic oils maintain smoother flow and offer protection in much colder conditions.
It’s also worth noting that engine oil doesn’t freeze solid like water. Instead, it thickens and becomes less flowable as temperatures drop, making it harder for your engine to start and stay lubricated.
But how can you tell if your engine oil isn’t flowing properly?
4 Warning Signs Your Engine Oil Has Thickened
If you spot any of these issues, then it’s time to have a qualified mechanic inspect your car’s oil flow:
- Difficulty starting the engine: When the oil thickens, you may notice the engine cranking sluggishly or needing several attempts to start.
- Rough or uneven idling after startup: If the oil has thickened, the engine may idle roughly for a couple of minutes after startup.
- Oil pressure warning light: Thickened motor oil can restrict flow through the oil pump and passages, potentially triggering the oil pressure light.
- Grinding or knocking noises: When oil can’t reach critical components quickly enough, metal parts may rub against each other and cause grinding or knocking sounds.
Next, we’ll explore the key factors that cause oil to thicken in cold weather.
4 Factors Influencing the Freezing Point of Engine Oil (+ Tips on What to Do)
Here’s what influences the way your engine oil responds to the cold:
1. Oil Type
Synthetic oils maintain fluidity in cold temperatures due to their uniform molecular structure, whereas conventional oils thicken sooner because of their larger, less pure molecules.
What to do: Use synthetic oil with a viscosity grade recommended for your local climate, such as 0W-20 or 5W-30 for colder regions.
2. Additives
Conventional oils thicken quickly in cold temperatures because they lack additives like detergents, dispersants, and viscosity improvers.
What to do: To ensure smooth circulation, choose oils labeled with “cold-flow” or “low-temperature performance” additives.
3. Engine Condition
If the engine is clogged with dirt or degraded oil, thicker oil will have more trouble reaching vital parts.
What to do: Keep your engine clean with regular oil changes and scheduled maintenance.
4. Parking Spot
Vehicles parked outside overnight are directly exposed to freezing air, causing the oil to cool and thicken faster.
What to do: If possible, park in a garage or sheltered area to reduce exposure to freezing air. If indoor parking is not an option, use an engine block heater to prevent the oil from thickening.
Curious about engine oil, its viscosity, and why timely changes matter? Explore our in-depth Engine Oil Guide.
Now that we’ve discussed preventative measures, let’s look at what you can do if the engine oil has already thickened.
How Do You Handle Thickened Motor Oil? (Especially if You Park Outside in the Cold)
If your engine won’t start because the oil is too cold, avoid forcing it to crank, as this can cause severe damage.
Instead, focus on warming the engine at your current parking spot. You can use a low-wattage electric heater positioned at a safe distance from the vehicle, or cover the hood with an insulated blanket to trap heat.
Keep Your Engine Oil Flowing Smoothly with AutoNation Mobile Service
Thickened oil can make your engine harder to start and more vulnerable to wear.
Want a hassle-free way to keep it flowing smoothly?
Try AutoNation Mobile Service.
Our trained technicians come directly to your driveway to inspect your oil and provide professional maintenance. For your peace of mind, we also back our services with a 12-month, 12,000-mile warranty.
Book an appointment today and drive with confidence, no matter how cold it gets.