Synthetic vs. regular oil change


James H. writes by email:

“I have a 2006 Cadillac DTS with 149,500 miles. Using the oil life monitor, I usually change my oil around 25% and/or about 5,000 miles. I have been using oil for cars with over 75,000 miles. Between these oil changes I use between a half quart to a full quart. It looks like I might be losing oil from around the oil filter. Should I change to a synthetic oil?”


Thanks for writing. Losing a quart between oil changes, I think, is perfectly normal for an engine with almost 150,000 miles. Ask your service technician to check the source of the leak, as it may be due to a leaking O-ring. I would suggest that you keep using what you are using and I don’t see the need for you to switch to an oil that is 100% synthetic. Interesting note is that any engine oil that has a “0″ in the viscosity such as SAE 0W-20 has to be synthetic in order to meet the performance standards.

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