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Hello

I just purchased my first diesel truck and pretty much know nothing about them so I am here to learn. I traded my 2012 Ram 1500 and purchased a 2012 GMC Sierra Denali 3500 with 98,000 miles on it. I have been told that 98,000 miles is nothing to worry about. Can't afford a new one so 2012 with those miles is what I have. I do love it, I love the sound of the diesel more than anything. Plus it will obviously pull my trailer better. I am curious if you knowledgeable gents (or ladies) can give me any useful tips as to just how awesome my truck is? It is stock now as far as engine goes, not sure if I want to tune or anything as I heard emissions might become a problem. Anyway, I know nothing about my truck right now other than i love driving it and I am looking forward to learning as much as possible.

Thanks!
 

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Welcome to the forum. The search tool will give you LOADS of info to help you increase you diesel knowledge.
 

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Welcome aboard.
 

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Welcome!
 

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2006 LBZ CCSB Leveled, Hypertech Programmer, 2008 LMM WT, 2008 Gasser WT
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Something VERY important to know about diesels. Diesel fuel is hydroscopic. That means it absorbs water. Avoid backwoods and ghetto gas stations. Gas stations that don't move a lot of fuel can have water and algae growing in it. Water going through your pump and injectors is VERY BAD. Be picky about where you get fuel. Going to shitty gas stations to save a few cents per gallon could end up costing a few thousand dollars in repairs.
 

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Welcome to the DF!
 

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Start by putting together a maintenance schedule for the truck based on the service records provided by the seller. If no records were provided then I would assume nothing has been done and replace the transmission fluid and filter and the motor oil and filter. There are good motor oils like Valvoline Blue and Pennzoil Long Life for diesels and expensive mediocre oil like Amsoil.

Diesels can have a turbo failure at 60,000 miles and injector failures before 100,000 miles are not rare so 98,000 miles is not actually low mileage. The front end has 8 places that should be greased every 3,000 miles to avoid premature wear and failure and with a new truck I would take it to a front suspension shop and have them put it on the lift and check it out. Actually it would have been wise to do this before buying a truck like this. There are permanent posts showing the location of the lube points.

Diesel fuel is extremely dirty and even if in theory it is 98.7% effective elimination of 4 micron size particles there are still 65 particles per milliliter of fuel making their way past the filter and into the high pressure common rail fuel system and striking the fuel injector solenoids at up to 42,000 PSI or very high velocity. 65 per milliliter works out to 240,025 particles per gallon of diesel fuel burned getting into the injectors. The 4 micron filtration figure of 98.7% is actually an exaggeration as it is based on lab tests with a static filter and are not reflective of real world performance. With a truck engine the filter is subject to lots of vibration which can dislodge particles on the filter media and let it into the fuel stream. There is also surge when the engine first starts and this surge will also cause more particles to get past the filter and into the fuel stream. And the filters that use a cellulose and glass media are subject to deterioration with glass particles getting into the fuel stream and into the injectors.

The moral is to not delay in changing out the fuel filter but also not to do it more often than the DIC indicates as it is metering the amount of fuel actually used which can vary widely. My truck with a trailer in tow gets 10-11 mpg as compared to 18 mpg on the highway with no trailer and so mileage is a bad way to determine when to change the fuel filter with a diesel engine. The display shows the actual gallons used and also the total hours of operation which is useful. Fuel filters are least effective when new (as with air filters) and before any loading of the media has taken place so changing more frequently than the DIC indicates is actually a bad practice.
 
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