Mystery tapping sound


I have just bought a 2004 Jeep Grand Cherokee with 40,000 miles on it. Only in the the morning or first startup I get this tapping sound. It only lasts about 20 minutes. The strange thing is you cannot hear this sound sticking your head under the hood,you can only hear this sitting in the car? Someone said it could be lifters,but at 40,000 miles?? Please someone help me!


Which engine? In neutral and/or drive. At what RPM? How dark is the oil on the dipstick? How thick is the oil on the dipstick?