I looked at the "Best Oil" sticky and thought I'd answer some questions to help find the answer to my own question—Which oil/filter combo should I use, and how long should I attempt to make my OCI? I am currently using whatever the dealer put in just over 1,000mi ago when I bought it. I just bought some Mobil 1 Extended Performance oil/filter on sale and am hoping to get a 1-year OCI because of my milage/year. 1. What kind of vehicle you have 2006 Jeep Liberty Limited 3.7L V6 42RLE auto trans 2. What your owner's manual says -- not just viscosity, but certifications (look for acronyms like API SM, ILSAC GF-4, etc.) and change intervals as well From the owner's manual: Change Engine Oil Road conditions as well as your kind of driving affect the interval at which your oil should be changed. Check the following to determine if any apply to you: • Day or night temperatures are below 32°F (0°C) • Stop and go driving • Extensive engine idling • Driving in dusty conditions • Short trip driving of less than 10 miles (16.2 km) • More than 50% of your driving is at sustained high speeds during hot weather, above 90°F (32°C) • Taxi, Police, or delivery service (commercial service) • Trailer towing • Off-road or desert driving If ANY of these apply to you, then change your engine oil at every interval shown in schedule “B” of the “Maintenance Schedules” section of this manual. If none of these apply to you, then change your engine oil at every interval shown on schedule “A” of the “Maintenance Schedules” section of this manual NOTE: Under no circumstances should oil change intervals exceed 6,000 miles (10 000 km) or 6 months whichever comes first. Engine Oil Selection (Gasoline Engines) For best performance and maximum protection for all engines under all types of operating conditions, the manufacturer recommends engine oils that are API Certified and meet the requirements of DaimlerChrysler Material Standard MS-6395. The manufacturer only recommends API Certified engine oils. Engine Oil Viscosity (3.7L Engines) SAE 5W-30 engine oil is recommended for all operating temperatures. This engine oil improves low temperature starting and vehicle fuel economy. Your engine oil filler cap also shows the recommended engine oil viscosity for your vehicle. Lubricants which do not have both, the engine oil certification mark and the correct SAE viscosity grade number should not be used. --- Schedule "A" says 6,000mi or 6/mo for OCI. Schedule "B" says 3,000mi or 3/mo for OCI. Since I do a lot of short trips (under 10mi) should I consider myself to be on the "B" schedule? 3. Where you live Western Washington (State) 4. How you drive (easy? hard? fast? slow?) I've heard for the best milage to try and keep it below 3k RPMs, so that's what I do. 5. What your daily drive is like (short trips? long trips? city? highway?) Mainly backroads and around town with the occasional highway trips when my wife wants to us take the Jeep because she likes it better than her 2009 Corolla S. To work and back (most days) is just under 10 miles each way on backroads, going about 40-45mph. According to my iPhone app (Gas Cubby), I drive an average of 30mi per day. This comes out to just under 11,000mi/yr. 6. Whether your car has any known problems No known problems. I just changed out the front and rear diff fluid with 80w90 Valvoline, and the transfer case and transmission (dropped pan and replaced filter) with Valvoline ATF+4. Runs like a dream.