The above post about Mobil I was supposed to be a new post. I clicked the wrong button. I will repost as a new topic.
You didn't say which engine (motor is incorrect) you turned backward. If it is a Diesel and you can turn it forward (2 complete revolutions), without the valves hitting the pistons, you haven't jumped the timing because on a Diesel if the timing chain jumps one tooth, the valves will hit the pistons. As long as the valves clear the pistons, it won't hurt to start the engine. If it runs as before, the injection timing didn't jump. If it doesn't run as before, you should retime camshaft and injection pump to the crankshaft.
My quess it that you won't have problem.
I'm not sure if the pistons will hit the valves on a gasoline engine with one jumped tooth. So the above test might not work for a gasoline engine.
Always turn the engine 2 revolutions in the direction of travel by hand if there is any question about timing. Even cranking the engine with the starter will break parts if valves hit pistons.
P E H