Does synthetic oil cause leaks?

Does Synthetic Oil Cause Leaks? Understanding the Facts and Myths

Synthetic oil provides superior performance and longevity compared to conventional oil. However, a common concern that persists is whether synthetic oil causes leaks in engines. This topic has generated much debate and confusion, leading many to question whether switching to synthetic oil could harm their vehicle. In this article, we will explore the facts and myths surrounding synthetic oil and leaks, providing you with a clear understanding of whether this concern is justified.

Here are the facts about synthetic oil and leaks

• Synthetic oil does not cause leaks
• However, if you have a leak, switching to synthetic oil may cause it to leak more.

When synthetic oil was introduced to the public, owners complained that their engines leaked oil right after they switched to synthetic. They blamed the oil, and from that point on, it became a well-known “fact” that switching from conventional to synthetic oil caused an engine to leak. But here’s what was really going on.

Where the myth comes from

Synthetic oil was first used in racing engines

Racing oils don’t contain detergents, dispersants, seal conditioning additives, or anti-corrosion additives. Why? Well, the answer is two-fold. First, they don’t need those additives because the oil in race cars is changed after every race. Second, because those additives take up space, a quart of oil is actually about 75% oil and 25% additives. If you don’t need the additives, and you really need the lubrication, why not get rid of the additives?

The problem came into play when owners started using those early synthetic racing oils in their daily drivers. The lack of seal conditioners and the fact that the oil flowed better at cold startup caused hardened seals to leak oil. That’s where the story got started.

Today’s synthetic oils contain all the necessary additives to prevent leaks.

All motor oil contains additives, including seal conditioners. If your engine wasn’t leaking oil before you switch to synthetic, it won’t leak after the switch. However, if your seals and gaskets are already leaking, switching to synthetic may cause them to leak even more, but only during a cold startup due to synthetic oil’s better flow characteristics when cold.

©, 2021 Rick Muscoplat