my 3.0 carravan engine 1999 is quiet when started cold after it runs about 2minutes the lifters start tapping as the engine warms up about 15 minutes the lifters quiet they will stay quiet all day even after cooling off thje starting again.but the next day the same thing happens i have used 10/30/and 5/30 oil i bought this used at 167000 miles it has always done this is possible weak pump?