After 5 years and 104000 miles, the engine failed. This motor has had oil changes every 3000 miles; and has had a synthetic blend oil used. It is a one owner car. It has never overheated. I had expected the Toyota engine to last several hundred thousand miles before repairs were needed. The engine design on this car is flawed. The very thin amount of metal between the cylinders does not allow enough surface area for the head gasket to provide the seal required for proper operation and long life. The 1.8 motor that Toyota uses in the Scion does not have adequate metal between cylinders; and is subject to blowing the head gasket. That is what happened to mine. The head gasket failed between #3 and #4 cylinders. That caused a 90% compression leak between these 2 cylinders. The metal on the head gasket between these two cylinders is completely gone. If you look at the head gasket picture; there are also burn marks between the other gasket gaps between cylinders. The symptoms to look for is an engine that is missing. Don't assume that the missing is caused by a bad coil or dirty plugs. If you try and run it for some time, water will eventually get into the engine and also ruin the block. After removing the valve cover and checking, the valves were moving as they should. At first it looks like there is a bad cylinder coil that is keeping one cylinder from firing. After checking and seeing that the valves are moving and that a new cylinder coil did not fix it; the mechanic proceeded to remove the engine head and found that the head gasket had a gap burned between 2 cylinders. The mechanic indicated that Toyota has a flawed design, and indicates now that the Scion has an abundance of problems with this engine. Of course the warranty expired at 100,000. The local dealer indicated that if I had the repairs done at the dealership; that Toyota might have helped on repair costs. Of course their dealer shop rate is almost double that of our local mechanic. Best advise is to not to get a Scion or Toyota vehicle!