Hey guys and girls. I recently purchased a 2011 jeep grand Cherokee Laredo with the penstar 3.6. It currently has 135000 km on it. I am mostly a short trip driver its under warranty thet require oil changes with dino oil every 3 k or three months or every 6 k or 6 months witb synthetic. Question is would it be ok to start to run a synthetic oil with it having 135000 km and not knowing the previous oil change history? Or would a high milage oil be more suited? Thanks in advance for all the help!