2012 Kenworth T800 ISX15 - Heavy Oil Consumption and Blue Smoke

Question

My 2012 T800 with 650k miles has started drinking oil. I'm putting in a gallon every 3 or 4 days. When I'm accelerating under load, I can see a blue haze in the mirrors, and it's starting to smell like burnt oil at idle.

The truck still pulls okay, but I'm worried about the DPF getting poisoned by all this oil. I checked the blow-by tube and it seems a bit heavy, but not 'engine-is-dead' heavy. I pulled the intake pipe off the turbo to look for oil pooling, and there is a little film but no pools.

FleetOwnerFiona · Accepted Answer

✅ Confirmed fix: Check your air compressor. On these Cummins units, the air compressor is lubricated by engine oil. When the rings in the compressor fail, it starts pumping oil directly into the air system and also back-pressuring the crankcase. I found a massive amount of oil in my primary air tank. Replaced the compressor and the oil consumption dropped back to normal levels.

WrenchMonkey_J · Answer

The ISX15 of this era is notorious for liner pitting and ring wear. How are your overheads? Sometimes a bad valve seal can cause this, but at 650k, you're in the window for an in-frame.

2012 Kenworth T800 ISX15 - Heavy Oil Consumption and Blue Smoke

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