I quickly becoming a big fan of the use of UV dye for finding oil leaks. My PU have been leaking oil and it was steady getting worst. It looked like either the oil pan gasket or rear main seal problem. I about to pull the engine when I did decided to run an UV oil test. Cleaned the engine and under carriage. Started the engine after pouring in he UV dye and look for the leaks which I found within minutes.
In my 50 yrs of servicing automobiles I have never seen an oil filter casing to leak but the Purolator One filter was indeed leaking near the area that the removal would fit. After removal I scraped off the paint in the two indicated leaks to find it cracked in both places. THe only thing keep it from leaking at first was the heavy paint job on the filter.
But at this me a day or two of labor pulling the engine.