Oil pan gasket

OK the two are not related. The O/F change has no bearing on this. However, in the observation of the mechanic, you have an oil leak and he has determined it to be coming from the oil pan. I would clean the engine very well at say a car wash and then watch the engine very closely to determine what is happening. Park in the garage and put a fresh piece of cardboard under the car. See if it leaks. Look at the car after it is now clean and driven home to see if any oil is visible and where. There are several places that could be the culprit of a leak. Oil pan gaskets usually don't fail without something causing them to fail such as the bolts not being torqued correctly, the pan being removed, the gasket being defective from the start. Look at the engine and let it tell you where the leak is.