Me being old school it took me a long time to get used to 10-30 motor oil. We just bought a Jeep Grand cherokee and it calls for 0-20. The 0 worries me and I would like to use 5-20. I just don't know if that's a good idea while under warranty. I will definitely use Mobile 1 as I have been for years. It has lifetime tranny fluid and that worries me too. Any thoughts?