What Are the Risks of Switching to Synthetic Oil in Older Cars?

The automotive community continues to debate whether switching to synthetic oil in older cars is beneficial or risky. In general, synthetic motor oil offers owners of newer cars, trucks, and SUVs multiple benefits, from extending component life to reducing cost of routine maintenance. If you have heard about the benefits of synthetic motor oil in vehicles, you may be inclined to switch. However, there are some risks you should be aware of if you own an older vehicle.

What is Synthetic Oil?

Before you consider making changing oil from conventional to synthetic, you should understand the differences between them. Regular or conventional oil such as Castrol GTX is made from crude oil and refined through a process that thins the viscosity of the oil to desired levels. Conventional oils may contain additives including zinc or ZDDP that help reduce cylinder wash problems common with conventional oils.

Synthetic oil like Castrol EDGE is created through a man-made process. It often starts as an extract or byproduct of crude oil, but then goes through much more refinement. Each manufacturer has their own method to combine it with other materials, chemicals, and additives to achieve the desired results.

Synthetic oil offers several advantages of conventional oil. It copes better with temperature changes and does a better job of effectively lubricating various components in the engine. It also provides more stability in cold temperatures and is more effective at cleaning out dust and debris from the engine. Synthetic oils can also be better formulated for specific uses, such as in high performance or high mileage engines. What's more, some manufacturers claim that using synthetic oil increases the intervals between oil changes.

Is Synthetic Oil Safe in Vehicles?

In the past, warnings were given about switching to synthetic oil because it could harm the engine. The reason for this was that many synthetic oils contained esters, which are organic compounds mixed with alcohol. This combination was often hard on seals in the engine, and would cause them to wear down and start to leak.

Synthetic oil technology has improved over the years, and most cars on the road today should be able to use either synthetic or regular oil, so long as the proper weight is used. In fact, some new cars require synthetic oil. However, one exception is with older vehicles, especially those with high mileage. The seals in those engines may not be able to handle the additives in synthetic oil. However, that doesn't mean it's impossible to switch to synthetic in an older car.

Tips for Using Synthetic Oils in Older Models

When using the term “older” to refer to cars, it means those manufactured before 1990 or so. The risk with these models is that the seals, gaskets, and other components often aren’t as tight as with newer models. Because synthetic oil does a better job of cleaning out sludge, it could remove deposits that are acting as seals. This could result in leaks that cause the engine to burn oil and require you to monitor your oil levels and replace it more often. If you don't, you risk damaging the engine or other components.

It’s not accurate to say that you should never use synthetic oil in an older car. In fact, Castrol EDGE High Mileage is a synthetic oil designed specifically for high-mileage cars. If the car has been maintained and is in excellent running condition, the synthetic oil may protect the vehicle and prolong its life. Also, anytime you change from conventional oil to synthetic oil, always make sure to change the oil filter with every oil change.

Signs of Problems with Synthetic Oil in Older Cars

If you decide to switch to synthetic oil for your older car, talk to a professional technician first. They may want to check over your vehicle and make any necessary repairs or replacements before making the switch. This will help protect your older model vehicle and ensure its long life and continued performance.


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