Is it safe to switch an older car from conventional to synthetic motor oil?

John Paul, AAA Northeast's Car Doctor, answers a question from a reader contemplating making the switch from conventional to synthetic oil.

The 2018 Subaru Outback, a vehicle that carries a zero percent financing offer in September.
The 2018 Subaru Outback, a vehicle that carries a zero percent financing offer in September. –Courtesy of Subaru of America via AP

Q. I have a 2008 Subaru Outback wagon with a four-cylinder engine; it has 114,000 miles on it. I also have a 2006 Toyota Corolla with 80,000 miles on it. I have always used regular/conventional oil in both vehicles, but I’ve been reading about synthetic oil from you and other experts for years. I have two questions: Can I safely switch to synthetic oil on both cars without any problems? And at the mileage and age of both vehicles, is it worth switching both in terms of cost and possible reduced engine wear?

A. I’ve used synthetic oil in my cars and anything else with a gasoline engine for more than 20 years and feel the benefits offset any cost. In just about every case, my vehicles didn’t start with synthetic oil, and I had no problem switching from conventional to synthetic. One of my radio listeners had an interesting take on moving to synthetic oil. He had an older Toyota and switched to a synthetic blend for two oil changes and then to full synthetic oil on the last oil change. During a recent cold snap where we saw temperatures around 10 degrees, he felt that his car never started easier or sounded quieter.

John Paul is AAA Northeast’s Car Doctor. He has over 40 years of experience in the automotive business and is an ASE certified master technician. Email your car question to jpaul@aaanortheast.com.