<< I've switched to synthetic for easier winter starting and back to regular oil for summer with no problems. >>
Hi Keith.

Some other benefits of a good synthetic oil include reduced sludge build up/an internally cleaner engine, superior high temperature engine protection, improved performance, reduced engine wear, lower engine operating temperatures, improved fuel economy and still other benefits. If you want the best for your vehicle, I'd recommend using a good synthetic oil year round.
Steve
17 Year Independent AMSOIL Synthetic Lubricants Dealer
www.lubedealer.com/HiTechOilCo