The old book recommends 75-90W but the manufacturer has changed to 10-30W motor oil. It is a matter of choice but all who change swear by motor oil and claim it shifts like butter. When I changed mine I hadn't seen the motor oil posts and did the traditional gear oil no issues. But then there is the thoght about the gear oil contributing to early failure of synchros so the preferred here is motor oil. Most use a synthetic and swear by it. So you have a choice but if I was changing mine I would run a synthetic motor oil from here on.
A forum community dedicated to Jeep Wrangler owners and enthusiasts. Come join the discussion about reviews, performance, trail riding, gear, suspension, tires, classifieds, troubleshooting, maintenance, for all JL, JT, JK, TJ, YJ, and CJ models!