I flip the washer over and use it twice.  They are cheap, buy 5 or 6 at a
time and keep them on hand.  5-30 is too thin for any vehicle IMHO.  It was
introduced as a gas saving viscosity.  I run 20-50 all year here in
Delaware and have had no problem starting in the winter.  My camper is not
a daily driver.  It was able to start last winter whenever I needed it.

                                                        Jay