I am in the process of buying an 84 celica liftback GT. WE went to drive it and it was a little rusty b/c it has been sitting for about 3months. But after it ran for a while we noticed this weird ticking noise. We took a look @ the engine and nothing was out of place so we unscrewed the oil cap and the sound got louder........What is it and is it a major problem. Other than that the engine made no noise and ran decent for having been sitting for so long. Could this just be a need for an oil change and a BIG tune up? Any advice would be helpful!