Just picked up a good condition 1995 Jeep Cherokee I-6 Cylinder XJ with 190,000 miles on it . I believe new it called for 5W30 oil ...Mechanic friend I talked to advised the following : * Might want to stay away from synthetic oil if your not sure what the previous owner(s) used ... High mileage Jeep I-6 cylinder engines are prone to real seal oil leaks with synthetic oil. * With 190K miles on the engine you may wish to go up to 5W40 in winter and 10W40 or 15W40 in the summer ... Don't overlook a HD oil like Rotella - will play nice in your high mileage 1995 Jeep I-6 cylinder engine . Your thoughts and advice ? - My knowledge of jeep engines and any engines in general from 1995 is slim .