Bob,
I am one of those "walking upstream.." kinda guys, I don't really have that many followers on these oil pages. I personally think that the 10w/30 oil is marginally ok in most circumstances, and I have never lived in cold enouph climates to consider myself in those circumstances. I use 10w/30 until warranty is up and then I start going thicker, I won't say that everyone needs 20w/50 oil, but in my circumstances, I will go with half 10w/30 and half 20w/50 in my newer vehicles after about 50k miles.
My currently oldest vehicle (89 Nissan truck with 185k miles) was using 10w/40 with added stp , (used 10w/40 since it was new and just added the stp after it had about 100k miles)...has never used oil by the way (3k oil changes..)
My 99 s10 ZR2 truck is actually getting BETTER fuel mileage since I started mixing the 10w/30 and 20w/50 oil...I don't know how to explain that (I check every tank, always have on every vehicle since they were new).
(I know that several people have a problem with mixing oil wts, but I don't and the mfgrs that I have checked with have told me that there is no conflict with additives, and that it may not be an exact average for viscosity...(ex-15w/40 in my case) but is close enough. I use normal Havoline oil and consider the Chevron/Havoline to be the current (high) standard that other oils try to compete with...but that's just my opinion. I have never used synthetics, and have never seen the need for them (Remember, I have also never lived in extreme circumstances either, hot or cold,,,I've always lived in the southeast, NW Florida years ago and central NC now.)
It's your call of course, but I for one do not hold 10w/30 oil in any particularly high regard.
I have never leased a vehicle, and typically keep vehicles until about 200k miles...I will probably keep the 89 Nissan longer though, it is my work/play truck now..
I look at it this way, Chevrolet wants me to go at least 36k with no problems, the government wants us all to get good gas mileage, I want to keep my vehicle practically forever...I put MY priority first not theirs...
good luck, and everyone having a great weekend???