anyone know what this sound is?

[fubu85]

Hey you guys. i drive a 00gt and it is pretty much stock. I noticed the last week or so, when i start my car i hear a loud fluttering noise....almost like sticking a poker card in a fan. it only makes this noise when i start the car and it only lasts about 2 seconds. It seems to be driving the same and everything so i was just wondering if that was a sign of a potential problem?

 

[sgarlic]

If it's coming from the engine compartment.. how many miles are on it, and what weight oil do you use?

 

[squares98]

rod knock?

 

[fubu85]

it is totally coming from the engine. Just cant tell where under the hood exactly. I think last time i got an oil change i put 5w30 in......i like in san diego so the weather is easy on my car