Synthetic Oil

I have a 96 Mercury Marquis with 121,000 miles that has always used 5w30 "regular" oil. My local service center that always changed my oil
closed, so I took it to the local Ford dealer for an oil change in May. 4000 miles later I have oil leaks, hardly nothing dripping (yet) but engine is now really wet with oil, hard to tell where it's coming from. I find out that the dealer used 5w20 synthetic oil.
If I go back to regular 5w30 will my leaks stop or do I have permanent leaks from this snythetic oil. I have read alot of different opinions on this oil but nothing about what will happen if I switch back.
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Grumpy snipped-for-privacy@msn.com wrote:

New synthetic oils should not be causing oil leaks.
However, if they are, switching back will solve the problem.
Jeff
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