My wife has a 96 Toyota Rav 4, 2.0 liter, automatic, with 113,000 miles on it. Up until 3k miles ago she had always used a local service to change her oil. After we got married I convinced her to let me change her oil and use Mobil 1. She drives back and forth to school every day. That is 145 miles round trip of 99% pure highway driving. Changed her oil to Mobil1, used a standard Toyota factory oil filter and everything was good. Last Friday she was driving home from school and was just about home when her oil light came on. She drove on home where luckily my Dad happened to be letting our dogs out for a "constitutional" He checked the oil and it was bone dry, not a drop on the dipstick. He checked everything out and there was no sign of leakage. There was no Mobil 1 around in my garage, I was out, so he walked back to his house, grabbed some Quaker State, and filled the car back up with oil. Everything has been ok since then. No sign of oil usage or leakage. The oil and filter will be changed this weekend so my questions are this. 1. Is this type of oil usage when switching to a full syn to be expected? It didn't happen in my Durango so I'm a bit concerned. 2. Should I go back to Mobil1 in her car or stick with a dino? Any other suggestions would be greatly appreciated.