I have a 98 Beetle which I just recently purchased with 58K miles on it. I had planned to change to synthetic oil (Mobile 1) and my next oil change. I had heard that I should flush the engine first and then do the switch. While at O'Reilly's today to check out the engine flush, I inquired about which product to use and the clerk said that I shouldn't switch to synthetic because it's too thin and will cause engine leak. This is the first i've heard of that. Any thoughts out there? Thank you all in advance for your knowlege.