Ticking/Knocking noise

I have a 1999 GMC Safari with about 106,000 miles. The engine is a V6 4.3 liter motor. Yesterday when starting up the engine, there is a loud ticking/knocking noise coming from the engine compartment. Does this for about 10 to 15 minutes and then when the engine is hot, the noise goes away. I am thinking that this might be a lifter problem but not sure. Does anyone have commets on this. If it is a lifer problem, how hard is it to change out the lifters?

If the lifters are actually making noise and it goes aways after it warms up, run some Gm engine crankcase cleaner through the engine and change the oil. Also add some GM oil supplement. If they are just dirty, this will fix the problem. When I have a vehicle making lifter noise, I usually follow this method above, and always have good results - so long they are dirty oly, and not any mechanical damage.

If the lifters are actually making noise and it goes aways after it warms up, run some Gm engine crankcase cleaner through the engine and change the oil. Also add some GM oil supplement. If they are just dirty, this will fix the problem. When I have a vehicle making lifter noise, I usually follow this method above, and always have good results - so long they are dirty oly, and not any mechanical damage.
Thanks for the reply. After talking to my good friend at Autozone, he suggested that I change the oil, and suppliment 1 quart of oil for 1 quart of Marvel Mystry Oil. So I did this and within 1 hour of driving the van, the noise went completly away. then changed the oil again about 300 miles later doing the same thing and the noise has never came back. Ever took the van on two long trips and it ran like a champ with no noise or problems.