I have a bone stock 93 Z28. The guy that owned the car previously removed the factory oil cap and replaced with an after market one. This is a dumb question but what kind of oil should I run in it, given that I live in Missouri and it's summer? 5w30 10w30?

 

5w-30

 

it calls for 5w-30 but my car has 153,000mi on it so i run 10w-40 in the hot summer time and 10w-30 in the winter.

 

royal purple 5-30 if you can afford it. i run it in my 95z and its the best oil iv ever used!!!