2017 3.6L Cold Start, Engine Noise, Rod Knock, Rattle?





I have occasional start up «rattle» in my 2017 LGZ 3.6L that is about the same as the 3.6L LFX. It is nothing like what someone posted with the Pontiac that occurred some 4 or 5 seconds After the engine was started.

The «rattle» is more prevalent in colder weather and louder, but in any case is immediately after the engine starts for only 1 to 2 seconds. Usually, the «rattle» is only heard for the first start of the day in my case. Now in Summer, I have not heard any discernable rattle at all.

Anyway, I am of the opinion that there is more than one type of «rattle» people are referring to regarding this.


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(Totalled) 2018 Canyon SLE CCSB 3.6L — King 2.5 coilovers | Icon 2.0 rear shocks | 1″ AutoSprings AAL | 2″ WULF Suspensions lift shackles | RC 1.25″ body lift | DV8 887 wheels | Milestar Patagonia LT285/70/17 | Custom bed rack |Tepui Baja Kukenam RTT | DV8 rear bumper | DV8 front bumper | Smittybilt X2O 10k winch | Morimoto HID | Tyger step bars | DV8 + ZR2 skids | Build Thread

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Arthur Kill


Pardon the late response, I didn’t have post notification activated. I’m not sure what the owners manual says about oil type options, I just used my understanding of oil performance and my suspicion as to what was happening to make the change. Briefly, the first number on the oil rating is the viscosity index at which the engine starts up near on a cold start. When the engine reaches operating temperature it will be operating at the viscosity index of the second number. In other words, as the oil temp changes, so does the oil viscosity and it is hard for metal parts to clack through thick oil.

5W30 is the designated range from the manufacturer for a number of reasons they have determined. Generally the colder the weather, the greater the benefit from the 5 index and likewise for the higher index as temps begin to rise. Some performance oriented cars have a factory recommendation to bump the oil viscosity up if the vehicle is going to be run at the track.

My reasoning for the change to 10W40 is for the added protection higher viscosity offers as well as how well the thicker oil hangs around in passages. My engine is started at a slightly higher viscosity, 10 and run at a moderately higher viscosity 40 when hot. With reasoning that the motor is started at the equivalent of a 30W30 when it is shut down using 5W30 and started up hot, 10W30 should pose no issue whatsoever.

The noise is definitely associated with the oil in my car. With 5W30 it starts just shy of the 3000 miles of use mark. With 0W40 it starts the day of the fresh oil change and occurs consistently at all startups following at least 3 hrs of being parked. With the 10W40 I have not heard the noise since I started using it and it has been a year now. So, thin oil = chatter, thick oil = peace.

I have no reason to believe the change will in any way hurt my motor. My recommendation to those having this abnormal chatter is to follow your warranty instructions and investigate the feasibility of trying a higher viscosity to combat the noise and decide from what you find whether or not to trial it. I use 10W40 Mobil 1 and 3000 mile oil change intervals.

The noise I first heard posted by the OP which is the same as I heard in my own motor, is present in the link to this youtube example to make sure we’re all on the same key;

That is not normal if anyone suggests that it is.

Thanks for posting but that’s definitely not my noise — or what I’ve interpreted by others descriptions here.