I have a 96 Jeep GC with the 4.0 engine, that only has about 86k. I bought it used, but ever since I've had it, I've been using 10w-30 dino, changing every 3000 miles. Occasionally I've put in 5-30 during an especially cold period, since I park outside in the Michigan cold. Now I'm thinking about going to Mobil 1, is there any reason not to do it? I would definitely benefit from the extended change interval since I'm now living in an apartment and dont have easy access to my tools anymore. What would be recommended, 10-30 year round?