What oil should I use?

[Benm109]

I just rebuilt my 305 engine in my 91 Camaro. Before the engine was rebuilt, the oil would get changed with 10w-30. Once I did the rebuild I put 10w-30 without even thinking about it. I think the car is supposed to use 5w-30. I don't know for sure (I don't have the owner's manual). Does anyone know what my car is suppposed to use and what oil I shoud use now that it is rebuilt? Thanks in advance.

[Performin Norman]

It's kinda your choice. My personal preference is to use a thicker oil in the summer and a thinner one in the winter.