Muffled clicking (pistons?) only under this condition

[maxlife]

Greetings. I'm new to the forum. My last three vehicles have been Maximas. I've had a '95, a '99 and now an '06 SE.

About a month ago I started to notice this problem. I bought the car 13 months ago with 30k on it and it now has 39k.

I have a 45 minute drive to/from work. When I start my car in the AM, everything is perfect. No noises that concern me. After it sits at work for 9 hours, I start it again - again no noises. Now, lets say when I get home I go inside, eat and then need to go somewhere. When I start the car after it sits for a short period ( <1 Hour )after being driven a while, I get a low muffled constant clicking at machine gun speed. The car is much louder under these circumstances. If the car sits 2-3 hours inbetween drives, I dont notice it. Has anyone experienced this? Is it oil breakdown related? Lack of cooling? Oil type? Where I bought it they only use Quaker State. Not sure of what type.

[maxlife]

I may have described that poorly, the noise occurs as soon as you start the engine the next time you drive. I never wait for it to stop, I just start driving and it eventually goes away.

[loystock]

Better buy a mechanic's stethoscope to isolate the problem. It's available from parts store, Harbor Freight and also on-line. It seems to early to have carbon buildup/gunk in the engine. If noise is confirmed from the engine, buy BG Quick Clean, apply on a warm engine just prior to oil change. You may have to do this on 2 consecutive oil changes. And better use synthetic oil - Mobil 1 and the likes.

Also, apply Red Line SI-1 or BG44K Fuel System Cleaner, do several WOTs on a highway (not necessarily breaking the speed limit). I've been using BG44K for a long time and switched to Red Line this year. Just apply every 6 months or whenever going on a long trip.