Re: so whats the best non-sythetic oil??
If you buy a brand name non-synthetic oil that has the highest SAE classification for a gasoline engine, that has the correct viscosity range for the ambient air temperatures where you live, and you use a good oil filter, and change the oil filter and the oil every 3 months or 3000miles, then you will get the maximum life out of your engine from a lubricating oil standpoint.
If you don't have access to an owners manual from a vehicle with your engine type which would have that neat little chart of oil viscosity versus expected ambient air temperature, then I think it would be safe to use 10W30 oil year round. Just change the oil and filter every 3 months or 3000 miles, whichever comes first.
For a general explanation of oil viscosity designation, the 10W30 means that the oil "behaves" like a thinner 10 weight oil at lower temperatures and it "behaves" like a thicker 30 weight oil at higher temperatures. So, basically, it can flow freely and easily to do its lubricating job throughout the temperature range that it's designed for.
The original owners manual for my 89 YJ with the 4.2L I6 calls for 10W30 for the temperature ranges expected in Virginia where I live. My 96 Chrysler Town & Country minivan with a 3.8L V6 calls for 5W30 for maximum fuel efficiency.
For oil filters, I use Purolator Pure One exclusively.