Well, Mobil 1 0w40 has served me quite well. I am going to dump it next week. I have put 5100 miles on it and it is my first run. I put on 90% highway miles, 10% short city. Well, I am taking a road trip in my 1995 Grand Cherokee this summer. Three friends and I will be driving to Seattle, Washington. Its about 2500 miles. Over 5000 miles round trip. My Jeep was voted over an 02 Taurus (due to lack of cruise control) and 02 Volvo S60 (due to lack of rear passenger leg room). I have no doubts that it will get there. I will be using FP for the road trip. I will be putting new tires (BFG A/T KOs... heavier than the Geolandar HTS i have right now so i'll suffer a little in gas mileage but it will be a 30inch tire over a 28.5 inch tire). OK. so OIL....
I have about 2400 miles left on the 7.5K oil change interval of the Mobil 1 0w40 (which UOA says is pretty good in terms of wear) but I am going to change it because it is the first run on Mobil 1. For this road trip, I will probably still have the Mobil 1 still in the oil pan by the time July comes around. Now, if say, I have 3000 miles on Mobil 1, would I be pushing it if I ran it for the 5000 miles road trip without having to change it? To ensure less miles on the second batch of Mobil 1 in my Jeep, would I be safe to change it next month, after the semester is over? I have to go home to change it and by then, I would have put on another 1200 miles on the Jeep. Opinions?
PS. i might switch to 5w40 because my friend says we will be climbing hills and see heat of 110 degrees. It is also easier to find.