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Discussion Starter · #1 ·
Is anyone stepping up the viscosity of their oil? I just bought a new 2016 Sierra and it's got either a valve tap or piston slap on cold starts. I'm thinking that a step up to 5w20 might help but I know it's not always a good idea on some engines.
 

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Not sure I see the logic in using an increased viscosity but would say not adhering to the GM recommended grade could have a bad effect if there comes a time you wanted warranty work on that engine. Is the noise with your engine not usual for that engine at cold start?
 

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I would take it to the dealer. Brand new truck shouldn't have either. Changing oil won't solve the problem.
 

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You really haven't stepped up viscosity by going with a 5w20. It and 0w20 are so close in cold flow and identical at operating temp. I don't have the Ecotec engine, but if I did, I would be using 5w20 right out of the gate. A 5w20 has a significantly lower NOACK (burn off vaporization rate) than a 0w20. And unless one is living in some very severe cold weather like Canada or Alaska, maybe upper Montana or N. Dakota, they have no real need for a 0w20.

Increasing viscosity would be going to XXw30 oil.
 

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There was a lot of chatter online about this when the 14's hit the road. I experienced the noise when new and still hear same today at 24k miles. I had concerns about it the first time I remote started it while next to it. You can really hear it. I don't feel it is piston slap in my case.
"The Direct Injection system is the cause, The rapid ticking noise on cold start up is the fuel pump (located on the rear of the left cylinder head) building up high fuel pressure. When the engine warm-up is completed, the high pressure fuel pump will continue to tick at a lower rate of approximately one tick per second during idle. The clicking sound is the fuel injectors pulsing on and off under higher fuel pressures. This sound is a normal characteristic of Direct Injection Fuel high pressure fuel system.

What I heard is not the old piston slap issue, there is a more distinct "click" to this noise than the piston slap.

Use a broomstick or a real long screwdriver/pry bar and listen to the noise (one end on the engine the other end against your ear) near the high pressure fuel pump and see if that is the patterned noise you are hearing. Piston slap is loudest (crisper) in the block, not from the head". If your noise is low in the block area, then maybe you have an issue. Being so new, I would go to dealer if you are still concerned.
 

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Discussion Starter · #8 ·
Thanks for all the replies guys. The reason I asked about increasing the viscosity is because I'm 99% certain that the noise I'm hearing is the dry valve train chattering for a second before the oil gets to it on a cold start. My thought was that the 0w20 is so thin that it almost completely drains/dries off the valve train overnight. I thought that maybe a thicker oil would fix this but I KNOW it's not always a good idea to do that on these newer engines. Thicker oil, by the way, will INCREASE oil pressure, not lower it. I was just curious if anyone had the same thought on this sound that I hear as I do. Maybe when I switch to synthetic in 500 miles, it will fix that split second noise. Otherwise, I'll pay it no mind....is usually, I'll find something wrong with everything lol
 

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going to 5w 2o wont hurt anything. Unless you live at the north pole. Try it your next oil change.
I had a f**rd van that called for 0w 20 and it clattered loudly at start up. I just ignored it but it never did go away. I didn't try 5w 20 s so I cant help you there. Never had a problem, just a noisy startup.
 

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GM has to factor everyone from the Panama Canal to Barrow, Alaska when they make their oil recommendation. Unlike many European and Asian auto manufacturers that don't assume their consumers are mental pygmies and the OEM provides guidelines for oil viscosity based on prevailing climate operating conditions etc. 0w20 is the extreme one size fits all thing that covers the worse cold scenario and keeps the EPA Nazis from coming unglued.

A 5w20 has a CCS viscosity of 3300 at around -30C/-22F (the rated temp of a 5w20) and a 0w20 has a CCS viscosity of 5000 at -35C/-31F (the rated temp of a 0w20). 5000 is more viscous (slower flowing) than 3300. At -20F like the 5w20, the 0w20 is virtually the same viscosity. No appreciable difference. At those low of temps, oil is but one of many problems when it comes to vehicle operation. Now, not very many folks in the continental 48 states of the U.S. deal with that cold of temperatures. They may think they do, because they confuse wind chill with ambient temperature, but wind chill only pertains to human skin, not equipment and oil. Those of us that do deal with those actual low temps from time to time usually have block heaters, oil pan heaters, battery blanket warmers, etc so that we are not abusing our vehicles. Some don't, but they pay a heavy price in the long run.
 

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ericlw said:
My 2014 truck with 0w-20 oil probably sits for 5 days at a time before its driven and i dont notice any strange noises from oil running off.
your'e in TX, here in northern PA every 2014+ truck I have heard start makes the same noise when its around or below freezing. Including mine, something to get used to.
 
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