I have a 92 Corolla that I'm using synthetic oil in. It has been in the motor for 30,000 miles. I've had no problems except now it has developed an oil leak behind the harmonic balancer. It doesn't look like the oil pan is leaking, it looks like it may be coming from the seal behind the front lower timing belt gear. Is this common and how do you pull off that timing gear? Can you replace the seal without removing the whole oil pump? I have never worked on one of these engines, but I do have a mechanical background and any tips you can give me would be helpful. Thanks!