Originally Posted by DanSSEi00
I use 10w30 synthetic blend. not a full syn. and Im partial to the OEM replacement AC Delco filter. You could also use a 5w30 if you are in a warm climate. I need the 10w30 cause my lifters make a ton of noise when its REALLY cold out.
You seem to be confused about the cold viscosity. 5w-30 is thinner at very cold temps (around 32 and below) than 10w-30, thus is suited for colder climates. It will pump better when cold, reaching the lifters quicker.
10w-30 doesn't have as great a viscosity spread, so is less likely to break down and go out of grade during use-- this is likely why GM specifies this grade.
Also, nearly all current AC Delco filters are made by the same company that makes STP, Supertech (Walmart), and many other filters. Most use an "E-core" design that is shared among the various brands. There'* nothing special about them, but if it helps you sleep better at night...