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Does Switch to Synthetics Cause 'Dry' Engines to Begin Leaking

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Does Switch to Synthetics Cause 'Dry' Engines to Begin Leaking
There seems to be lots of disagreement across various web message boards about the effect of a late change to synthetic oil on engine seals -- all based on anecdotal experience. Is there any scientific basis to support or refute the claim that synthetics can cause "dry" engines to start leaking? Has anyone ever conducted a controlled study on this topic? I'm trying to figure out what to do to my '98 BMW 740i with 126,000 miles which I'd like to keep until I get it to at least 200,000 miles.
-- Kent Bauman, Tucson, AZ
Synthetic oils meeting OEM (original equipment manufacturer) and Industry specifications do not cause leaks as they are tested to ensure that they are fully compatible with the elastomer materials from which automotive seals and gaskets are made. We are not aware of a controlled study on this topic.
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