This doesn't have anything to do with wheels & tires so I'm moving it to General Tech.

Can you give any further description of the sound? Does it fail to start? Does the sound go away as it warms up? Goes away gradually or suddenly?

 

 

A few questions:

• How many miles on the engine?
• Have you had the valves adjusted?
• What is the oil level in your engine?
• How long since you've changed your oil?
• What kind and grade of oil are you using?

 

 

Yikes! You're running 20W-50 oil in a 2007 V6 Honda engine? Get that stuff out of there now! Change to something like a 0W-20 and I'm guessing your start-up noise will be gone.

 

Without a sound clip or video it's tuff, but I'm guessing timing belt tensioner rattle. Has the timing belt (and tensioner) been changed? My 03 V6 would make the rattle sound on first cold start up. The sound would fade quickly as the engine warmed up. I changed the timing belt, tensioner, water pump, both pulleys, and coolant, and the noise was gone.

I'm hoping the 20w-50 was a type-o or something. I used the required 5w-20 in the 03.