low on oil

Timing chain .

it only has 78k miles, could it be because of low on oil? it's on 0w40, going to change it to 5w40 in a couple of days without driving it. the timing chain will be the job to take the engine out, wouldn't it?

I have a 07 with 120,000 miles that has rattled like that since it had less than 100k on it. Mine only does it after it has sat at least over night, and then only occasionally. Do a search on line, there is quite a bit of info on the problem. I believe it is one or more of the cam adjusters. It can be repaired with the motor in the car.

Some things it is NOT. 1)Piston slap--goes away much too fast, 2) loose wrist pin same as 1) ,3)loose connecting rod bearing is much too high a pitch.
Potential causes 1) internal leak in hydraulic timing chain tensioner, allowing chain slap on start--low probability because sound is one surface hitting another, not a multi-parts rattling; 2) collapsed hydraulic valve lifter--moderate-high probability ; 3) defective cam timing adjuster--highest probability a known issue try to locate it to one side, one cam by careful listening on cold start.

IF the noise does NOT quiet in 5 to 10 sec, do not drive!!! A broken cam chain or non-turning cam adjuster will wreck the engine immediately.It if does this every cold start, cam adjuster most likely. A valve lifter not likely to always be under load holding valve open and leaking down the same.

leaking tensioner wasted the pin in the passenger-side phaser because of low pressure. It's a staple.

In the end of that theme... camshaft journals in the back go dry for a short while... new heads or 1800car4kids.

All these troubles courtesy of these special tensioners
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