Both of my cars have notorious Hydraulic lifter tick, just like straight6 said, has to do with the oil getting to and pressurizing the lifters, also, to what lonnied said, it's worth a shot maybe, but I've heard that MMO is hit and miss for lifter tick, a lot of the DSM guys do a couple of oil changes with it and it helps, others not at all. Didn't help in my DSM, and in the Miata, I just changed the oil, and even on cold starts it quieted down a good bit. Granted, I did go to a slightly thinner oil.