Hi I was wondering about these three oils. I don't wan't to go synthetic and where I live these three oils are the most easy to get. I own a 2000 Jeep Cherokee Sport with a 4.0 engine. I previously owned a 1993 Geo Metro and always ran Castrol GTX. The engine had 233,000 KM when I sold it and it ran strong. (for a 1.3litre) Anyway I would really appreciate some input on these brands. Actually Valvoline and Castrol would be the easiest for me to purchase. (I live in NB, Canada)