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2020 Silverado RST crew cab 4x4 3.0 Duramax
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I plugged mine in when it was 6F. I thought it would help the next morning. I was wrong. The check engine light came on and my fan wouldn’t stop running on high. Stayed that way for two day before I could get it into the dealership. They said because I plugged it in when it wasn’t really needed it threw the code which kept the fan on. Makes no sense but that’s how it is. So I threw the cord under the workbench in the garage and don’t plan on using it. I’m in east central ohio so I does get pretty cold in the winter.
 

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I plugged mine in when it was 6F. I thought it would help the next morning. I was wrong. The check engine light came on and my fan wouldn’t stop running on high. Stayed that way for two day before I could get it into the dealership. They said because I plugged it in when it wasn’t really needed it threw the code which kept the fan on. Makes no sense but that’s how it is. So I threw the cord under the workbench in the garage and don’t plan on using it. I’m in east central ohio so I does get pretty cold in the winter.
There's an update to correct that but I don't recall the TSB #. Plugging it in when it isn't cold enough does that. Ohio doesn't get cold enough (or hasn't recently) to need it. Mine is still in the backseat storage where it was when I bought the truck.

 

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2020 Silverado RST crew cab 4x4 3.0 Duramax
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Good to know! Thanks for the info. I’ll have to get it into the dealership for the update.
 

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The block heater isn't just there to allow the truck to start. Having the oil warmed up before starting it will make it less viscous and hence flow more freely and reduce oil pressure. Sure, the truck will start just fine at -20F but over the long run those cold starts probably aren't the best thing for the cylinder walls, rings, etc.
 

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The block heater isn't just there to allow the truck to start. Having the oil warmed up before starting it will make it less viscous and hence flow more freely and reduce oil pressure. Sure, the truck will start just fine at -20F but over the long run those cold starts probably aren't the best thing for the cylinder walls, rings, etc.
I’m not as worried about 0-20w as I would be 15-40w for cold temp viscosity.
 

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I just got my '22 Silverado 3.0 this weekend. I am in Atlanta so we don't have too much cold weather - but there are a few days per year. I have had a diesel the last few years but it was smaller and fit in my garage. This truck doesn't quite fit and will have to stay outside so I have a couple of new questions. At what temperature should I use a diesel fuel additive? At what temperature and duration might I need to use the block heater? Is there a thermostatic switch available that can be attached to the block heater or extension cord to only turn it on below the specific temperature so it doesn't have to run excessively or all night?

Thanks in advance.
Not familiar with the new 3.0, my 2014 Savana 6.6 remote started the other day at 5 deg. F. I have never plugged in,
truck sits outside and has always started, good quality interstate batteries is all it takes here in MI
 

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The 3.0 will start as good, and maybe better, than the Savana in cold temps.


Cut/paste from a bulletin on the 3.0...

Also inform the customer to avoid engine block heater use in temperatures above 0°F/–18°C. While the owner’s manual states an engine block heater should be used in temperatures less than 0°F/–18°C, it isn’t vital until much lower temperatures of less than –13°F/–25°C.
 

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So this begs the question….does it cause issues/codes if used above 0F? Or “Just really doesn’t need it” ?
 

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So this begs the question….does it cause issues/codes if used above 0F? Or “Just really doesn’t need it” ?
It did prior to a programming change.

Here's the rest of article the previous post was taken from.

Cooling Fans Running for an Extended Period – TechLink

Cooling Fans Running for an Extended Period
December 13, 2019
Some 2020 Silverado 1500 and Sierra 1500 models equipped with the 3.0L diesel engine (RPO LM2) (Fig. 12) may have the engine cooling fans running continuously for an extended period of time. The Check Engine MIL also may be illuminated.

Fig. 12

Currently, an engine calibration in the Engine Control Module (ECM) will falsely set DTC P0111 (Intake Air Temperature (IAT) Sensor 1 Performance), which occurs when the engine block heater is used in ambient temperatures above 0°F/–18°C. As a result, the cooling system will go into remedial action and turn on the cooling fans at 100%. The remedial action will continue until the engine goes through a six hour cold soak.
If this condition is found, clear the DTC and return the vehicle to the customer. Do not perform any further diagnosis or replace any related components. An updated calibration will be available shortly.
Also inform the customer to avoid engine block heater use in temperatures above 0°F/–18°C. While the owner’s manual states an engine block heater should be used in temperatures less than 0°F/–18°C, it isn’t vital until much lower temperatures of less than –13°F/–25°C.
 
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You won't need additive or block heater in Atlanta.
Same thing they said about TX until it hit 2 F. Most diesels would not start due to gelling. Shelves were empty of additives.

They probably don’t have winter additives in retail fuel sold in Atlanta.

I would suggest having additive on hand and watching the weather forecast if you need to drive in low temp conditions. I lived in Atlanta and would not drive when slick…..total driving mayhem. Although I love to drive in the snow.
 

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Diesel fuel additives are snake oil and will do nothing for your engine, other than drain your wallet. Buy good quality diesel, normally from a commercial truck stop is the best bet. Modern diesels will start unaided down to a very low temp, probably 0f, in Atlanta I doubt you will ever need to plug your truck in.
Apparently snake oil keeps fuel from jelling in low temps. TX saw 2 degrees last Feb. and local fuels are not the winter blend. Many neighbors with diesels would not start due to fuel jelling.

If you live in a warm climate that gets unusually cold, buy the snake oil.


Sent from my iPhone using Tapatalk
 

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Same thing they said about TX until it hit 2 F. Most diesels would not start due to gelling. Shelves were empty of additives.

They probably don’t have winter additives in retail fuel sold in Atlanta.

I would suggest having additive on hand and watching the weather forecast if you need to drive in low temp conditions. I lived in Atlanta and would not drive when slick…..total driving mayhem. Although I love to drive in the snow.
Mine starts just fine down to -13* without a block heater, now fuel is a different issue, i’d have additive available.
 

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I wouldn't trust what the fuel stations "tell" you they put in there, I'd go ahead and run a good additive. I've found that Optilube XPD which was recommended by folks on here has worked great for me. I get it off of Amazon.
 
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