Switching oils

[Daniel Hussey <GY3WSX@vm.sc.edu>]

    Not to start a mega oil thread again, but....

    I'm currently running winter wieght 5W50 Castrol Syntec in my car.  Over
due for an oil change, but want to switch to a thicker weight for summer.  I
just bought some Castrol Syntec 10W30.  Do you listers think this is enough
for summer.  Summer's in Wisconsin are rather mild and don't typically get past
the 80s.  Just want to see what most of you use in the summer.

    Should I be switching to a 15W50 or 20W50 instead?  I have in the past made
my own synthetic blend using Castrol Syntec 5W50 and Castrol GTX 10W30 for the
summer.  Castrol now makes the Syntec in 10W30, so I'm going with that for now.
Unless I hear other suggestions from listers.

    I've also recently heard many people say that using a broad rance 5W50
motor oil is bad!  Is this true?  I only run it in my car during the winter
when I want a lighter weight oil so it will lube up the motor quicker at
start up.  BTW, I ran 5W50 Syntec exclusively in my old car and didn't have
any problems with it.  Just want to know what other options I want for a winter
weight oil if I want something that is lighter.

    Does anyone have any impressions on the new 0W(30?) Mobil 1 oil?  I think
my dad ran that in our A6 this winter.

    Later,
    Dan