Hello. This is my first post. I have a '97 Wrangler tj 4 banger with 100,000 miles. Doesn't use oil and has good oil pressure. Several days ago I had my oil and filter changed and the mechanic put in 20W50. I had been running 10W30. Now I hear a slight clicking or tapping noise when I crank up and it increases (not in volume)as I accelerate until road and wind noise drowns out the engine noise. Could the heavier weight oil be causing this and where would the noise be coming from--valve, lifter, or oil pump? Should I immediately change back to 10W30 or wait until my next oil change (2,500 miles)? Sorry for the lengthy questions.