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Discussion Starter · #1 ·
New member to the forum and first time diesel owner. Just purchased an 08 Sierra 2500 HD. The truck has 116k miles and a leveling kit. Otherwise it’s completely stock. The milage is low for the year and the truck is in fantastic condition both inside and out. Hope to get many years of great service. Is there anything I should watch for in a used LMM? Common problems that I can fix if caught early? I’m a fairly decent shade tree mechanic for gas engines and I’m confident I can make it through the learning curve of switching from a Vortec to a Duramax. Any advice or pointers would be greatly appreciated.
 

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Welcome aboard.
 

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Welcome to DF. So with the LMM, you have the first generation of the DPF systems. With this generation, the way the truck cleans the DPF is by dumping fuel into the exhaust stroke which heats up the exhaust and burns off the filter. This can and has cause fuel dilution in your oil. If you are unsure of the history on the truck I would do an oil analysis to see what the fuel dilution is like and check it every so often to make sure it is not getting worse with age. Beyond that, you have a solid truck. The LMM is the 4 generation of the Duramax and is a solid engine. Some will say delete and tune it but honestly, unless it is causing a lot of fuel dilution I would keep it stock.

With all diesels you have to keep up with mx, especially the fuel and allison transmission filter. Typically we recommend changing both about every 10k miles. Fuel pressure and a dirty fuel filter can cause the truck to do all kinds of stupid things. The Allison is a rock star. It will last a long time if you take care of it. Again if you are not sure on the service history, I would start on swapping out all fluids and filters just to make sure they are fresh.

If I can be of assistance, please don't hesitate to ask.

Take care,
 

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Discussion Starter · #7 ·
Thank y’all very much for the replies. Looking forward to learning more.
 

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Welcome to the DF!
 
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