AI have to agree with using the Mobil 1, but I would not recommend the semi synthetic anything because it only uses a very small percentage of synthetic. Only enough to stabilize the oil a bit. If you want to keep the car for a long time, I recommend using the full synthetic because it doesn't break down as fast, suspends more particles, and leaves no deposits. Even with hard use it's ok to leave in for 5-8K. Just make sure you're not using a cheap (fram) oil filter. The Toyota filters are best to use. If you don't like using synthetic, one of the best mineral based oils to use is Texaco Havoline. It has the least amount of Paraffin. All Pennsylvania oils are high in Paraffin and will leave deposits.