Re: switching to synthetic
There souldnt be a problem as long as your vehicle has had proper maintenance over the miles. In you climate, I would think you could use a 10W-30 Mobil 1, or Pennz, or whatever. Ive read that the 4 liter Jeeps like 40 weight, but generally that is if you are using a little oil to start with, I am personally using Amsoil now of course and using a 5W-30 in my Ranger that tows an 18' (glass) Bass Tracker, unsure of the weight. I changed it over to synthetic at 140,000, no problems, the first synthetic I used was Mobil1 10W-30. I like the Amsoil as it tends to thicken a little as it gets older and more miles, it starts out as a heavey 30 weight and ends up a light 40. I just changed it out at 8,500 Miles. Unless you are using oil now, I would not reccomend anything heavier. Im learning that the old addage of using a heavier oil just because you have more miles isnt necesarily true, as in thicker is better. Its not proving to be true as most thought, including myself. Use a good filter such as the Pure 1 from Purolator, the Mobil1 filter is good , but way over priced.