Why is my 2008 LMM stuck in a continuous regen cycle, and is my high oil level going to kill my bearings?

[GlowPlug_01]

Hey guys, need some serious diagnostic help on my 2008 2500HD (145k miles, stock emissions). Lately, the truck is entering active regeneration every 100 miles instead of the usual 300-400 miles. But here is the terrifying part: I pulled the dipstick today and the oil level is almost an inch above the full mark, and it reeks of raw diesel fuel.

I know the LMM doesn't have a 9th injector and squirts raw fuel into the cylinders during the exhaust stroke to heat the DPF, but is this amount of oil dilution normal when a DPF starts choking out? Or do I have a cracked Siemens injector nozzle bleeding fuel into the crankcase while parked? Am I going to wash out my main bearings if I keep driving it to work?

 

[Tonne_Tom02]

To answer your question directly: Yes, keeping driving this truck to work WILL kill your engine, and very quickly. One inch over the full mark means you likely have 2 to 3 quarts of raw diesel thinning out your 15-quart oil capacity.

Diesel fuel destroys the viscosity of motor oil. Your high-load components—specifically your main crankshaft bearings, rod bearings, and the flat-tappet lifters—rely on a thick hydraulic cushion of oil to prevent metal-to-metal contact. Right now, your oil has the viscosity of water. Under towing or even just highway cruising, that thin film will tear, causing immediate bearing scoring, spun bearings, or worse, an engine runaway where the engine starts running on its own oil vapor until it blows up. Do not pass go, do not drive it to work tomorrow. Drain that contaminated oil immediately and put in fresh 15W-40 before you do any further testing.