A Quality Filter and Synthetic Oil is the Best Lube Option for Cold Starting a Vehicle In Freezing Temperatures
Synthetic oil is the best lube option for cold starting a vehicle. Period. If you live in a frigid climate – as in, most mornings start at sub-freezing temperatures close to -18ºC between the months of November and March, you’re going to want to seriously consider switching to synthetic motor oil if you aren’t already there. To understand the logic behind that statement, it’s helpful to understand the internals of a typical ICE (internal combustion engine) and the path that oil takes within the engine when it’s added through the fill hole at the top of the valve cover.
How Oil Travels Through An Internal Combustion Engine
With the help of gravity, fresh oil poured through the fill hole on a valve cover begins to flow down to the bottom of the oil pan. In the bottom of the oil pan is something called a sump strainer, which is essentially a loose-weave metal screen that acts as a pre-filter before the oil pump and filter. This screen helps prevent really large pieces of debris, typically up to 1/32 of an inch, from clogging up the oil pump. A pickup tube is attached to the strainer and runs directly to the oil pump. Through this pickup tube, the oil pump pulls in oil under low pressure and compresses it to a very specific high pressure reading before a spring-loaded valve allows it to leave the pump and enter the oil filter. The oil first enters the filter on the outside of the filter media but is quickly forced through the media because it’s under high pressure. This action is what filters harmful dirt and other contaminants out of the oil. Once filtered, oil then flows from the center of the filter to the various oil galleries within the engine block – feeding all rods, bearings, camshaft, drillings and rockers, etc… From there the oil simply drains into the oil pan where the oil flow cycle is repeated for as long as the engine is running.
Now that we have a better understanding of the path that oil takes and the components that are affected as it makes its way through the engine, it will be easier to understand why synthetic oil is far superior to conventional oil when cold starting an engine in sub-freezing temperatures. To clarify, when we mention “cold start”, we’re not referring to starting the car in cold weather at any time. Rather, a cold start indicates the first time the vehicle is being started after sitting for a long period of time, such as overnight.
There are a few key issues that arise on a frigid cold start with the use of a what is, at that time, a greatly thickened, slow-flowing conventional oil.
1. Viscosity is Significantly Increased
Viscosity is defined as resistance to flow. The colder the temperature, the more viscous the oil will be and as such, higher viscosity means the lubricant will flow slower. Therefore, the viscosity of the oil is directly affected by the ambient temperature of the engine block during startup. If the engine block is as cold as a block of ice the conventional oil in the pan is likely to be extremely viscous with a consistency similar to that of molasses or syrup that has been stored in a refrigerator. This happens because the paraffin or waxes used in conventional oil solidify when the temperature drops. Conventional oil simply won’t flow normally until the engine reaches operating temperature. What this means is that there will be a period of time where the engine is operating without lubrication – needlessly increasing wear. There is no universe in which this scenario is good for an internal combustion engine.
2. Oil Pump Functionality is Negatively Affected
The oil pump is what keeps oil circulating throughout the engine after good ol’ gravity has done its work. It starts working as soon as the car is started and is supposed to get the oil moving immediately – pulling oil through the line connected to the sump strainer which we learned about earlier. This is an easy task for a properly functioning oil pump when the oil viscosity is at the right value. However, if conventional oil is used, we have to consider how the increased viscosity will affect the pump’s ability to pull oil out of the pan through the strainer. You only need a basic grasp on physics and fluid dynamics to figure that the pump is going to have to work much harder if the conventional motor oil is thick and slow-moving due to the cold. This doesn’t bode well for the longevity of the oil pump.
3. Oil Filter Functionality Could Be Affected
The next component that the oil will need to flow through is the filter. The oil filter is usually connected to a housing which is connected to the oil pump. Considering the negative implications for oil pump performance when using cold, thick, slow-moving conventional oil we can assume that the oil is going to have trouble moving through the oil filter media. The viscosity is just too high on a sub-freezing cold start. Luckily most oil filters feature a bypass valve which will allow oil to move through the filter, effectively bypassing the media in the event that it is completely occluded, or the oil is too thick to pass through efficiently. Still, oil filter functionality is affected by the poor flow of conventional motor oil in frigid temperatures – if only briefly. This might not be the worst thing in the world if the oil is brand new and clean, but later on in the time before the next oil change, you probably don’t want all that dirty oil passing through the engine unfiltered. Repeat this every morning when the car is started during the winter and it could take a toll on long-term engine health – especially if you’re someone who starts the car, immediately puts it in gear and drives off!
Synthetic motor oil flows freely even in sub-freezing temperatures, whereas conventional motor oil solidifies like molasses or syrup that’s been stored in a refrigerator. Which scenario would you guess is the better option for an engine during a cold start in frigid weather?
Synthetic Oil Saves the Day… and Your Engine
There are scores of reasons why motorists should consider using synthetic oil, especially in cold climates, but we only care about one for this discussion: Improved Cold-Flow
Unlike conventional oil, frigid temperatures have very little impact on the flow-rate of synthetic oil. This is because synthetic oil doesn’t use any paraffin or waxes that cause conventional oil to solidify when the temperature drops. For maximum engine protection, oil must flow quickly at startup. The dramatically improved fluidity of synthetic oil in frigid temperatures resolves all three of the previously discussed issues for motorists who use conventional oil and routinely cold start their vehicles in extremely cold climates.
Match Synthetic Oil to A Synthetic Oil Filter
It should be clear by now that synthetic oil is the absolute best choice of lube for anyone starting a vehicle in cold weather, but make sure to use the right filter with it. Believe it or not, there are oil filters engineered specifically for use with synthetic oils. One of the benefits of synthetic oil which we previously ignored to instead focus on cold-flow properties, is that it offers much longer lasting engine protection than conventional oil. In order to take full advantage of that benefit the filter media needs the ability to hold about twice as much dirt – and the other filter components need to be able to endure change intervals up to twice as long as what a conventional oil filter is capable of. Synthetic oil filters are the only filters that have these unique features for added engine protection. Why use the best possible oil in an engine, only to go ahead and use a sub-par filter that will probably fail well before the oil life is over? You wouldn’t because the idea defies logic. Make sure to use a synthetic oil filter with synthetic oil.
At the time of this writing there are 68 days until spring. Many of those days could bring sub-freezing temperatures depending on the location and it’s never too late to make the change to synthetic.
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