I have a 1999 Jeep Cherokee, 4.0L. I've used different brand oils for the past 2 oil changes I got (I've only had the car for less than a year). First time I used the store brand oil from Advance Auto parts, which was 10W-30. Then I used 10W-30 again, but I got penzoil. I'm just wondering which oil (penzoil, mobil, castrol, etc.), but also which oil TYPE you think is the best (10W-30, 5W-30, etc.). I don't know a lot about cars, so I just want to make sure I'm using the right oil.
