I was looking at plugs for my 2006 Lacrosse 3.8. I already ordered ACDelco wires. Everyone says that GMs run better on Delco plugs, specifically the ones that came on the car. O'Reilly lists several Delco numbers: -ACDelco "conventional" 41-601 ($2.49) "conventional", whatever that means. -ACDelco Professional Platinum 41-902 ($6.49) -ACDelco Professional Iridium 41-101 ($6.99) I want to stick with ACDelco. The car has 140K, plugs may be original and wires are original. I want to keep the car for a while definitely, and would like longer life (100,00 miles would be good). SO, which plugs? I have no problem spending $7 a plug, but what's the difference? I've looked and all the forums people say "use OEM". But these are all OEM. And would the life be 100,000 on them all? I don't want a "fancy" plug that doesn't work as well as what I have now. Thanks everybody! **O'Reilly lists a 100,000 mile warranty for each plug. Clear as mud.