A lot of people are suffering from that lovely slight knocking at start-up. I have an 09 with 10k on it and its been doing it from day one. Well i found a cure...lucas oil treatment! The 32 oz. White squeeze bottle. Its been two weeks and i live in michigan so its down to 30 deg. At night and it hasn't done it since! I even run mobile 1 and it was still doing it. I'm gonna just add it after every oil change. It ranges from $9-$12. I THINK WALMARTS THE CHEAPEST!

 

What octane gas do you run?

 

If it only knocks or "rattles" for a second on a cold startup, it is probably your timing chain tentioner, which is a warranty repair.

The tentioner is actuated by the engine oil pressure vs using a spring mechanism. On a cold start, as in the engine has sat overnight, the tentioner will be loose and the chain will slap against the housing until the pressure comes up. What can happen is over time the chain will stretch but not enough for the tentioner to move up to the next cog or ratchet position as it is designed to do to accomodate the stretching.

 

Or, it is the normal sound of an all aluminum engine with PCM controlled VVT cold start strategy program.

I'll spend your Lucas $$ on beer and not loose sleep over it.

 

i never really lost sleep over it, i just really didn't like a new motor clattering. its under warranty so no biggy but what ever it was its gone now. i don't really think variable timing had anything to do with it but ....like i said it doesn't do it anymore...

 

octane should only matter when the engines under a load hence spark knock, not at start-up, needless to say i have used premium also to no effect.

 

update! truck sat two days , was 29 deg. outside , started it up........no knock! gotta love the LUCAS! if it was the timing chain tensioner it would have knocked. no oil treatment will stop that. go figure....

 

which lucas oil treatment did you use? Did you use the full quart replacing one quart of oil? Would switching to 10w30 instead of 5w30 solve the knocking problem?