OIL, , , , , and a can of worms
I'm sure this opens a can of worms but , , , , ,
I have 3 cases of Castrol 5W-30 Motor Oil. It's about 5-6 years old. I used it in my old Toyota. I drive 20,000 mile per year to work. I was changing oil every 3,000 miles. I bought the Jeep with the diesel and I ran full synthetic 5W-40 and only changed the oil about every 7,000-10,000 miles. The Castrol sat on a shelf in the box.
I now have the Ford. 4.0L 6 cylinder. Ford dealer reccomends oil changes at 7,500. Not sure what the owners manual says.
My 2 questions are:
What should my oil change intervals be. 90% is interstate driving, 40 miles one way everyday M-F.
Do you think the Castrol 5W-30 is still good and is it good for the Ford, or should I get new AND should I go synthetic?
Guess maybe this is 3 questions.
I had intended to use the oil up that I have. Would probably last me the life of the truck (as long as I own it)