I have a 2007 S60 with 136k miles on it. When the temperature gets to mid-20s or below, the car has trouble starting. Engine cranks but takes 4-5 attempts before turning over. I hear a dripping noise between attempts. Once the car starts in the morning, I usually don't have any trouble starting it for the rest of the day.

Put a new battery in a year ago, new spark splugs a couple weeks ago, new timing belt and fuel filter last week. Also put fuel injector cleaner in the gas tank a few week ago.

Had the spark plugs done at a local garage, and took it back to a dealer for the timing belt. When I asked the dealer about the car having trouble turning over in colder weather, they suggested the issue might be that the shop that did the spark plugs used after market parts instead of volvo parts. I'm reluctant to rip out spark plugs that were just put in and put new ones in for another $200. The dealer was pretty honest on the timing belt, told me the water pump was bone dry and didn't need to be replaced so I didn't get the impression they were into recommending unnecessary work.

Anybody have any other suggestions?