Engine has 396k miles, second owner since 114k miles. Issue: when engine is warmed up, heavy grey smoke at idle, smells like burning oil. Found very dirty fuel in both filters, ran tank dry, changed both filters, filled with Diesel purge and refilled fuel tank with clean fuel. ( footnote low fuel light didn't work for first time) pre filter looks clean after 100miles but still have gray smoke at idle or initial acceleration.
Any thoughts?

 

Does the smoke burn your eyes?

 

No but smells bad like burnt oil, very gray

 

I would do a compression test, how is oil pressure?
Burning oil is usually has a blue (ish) tint though

 

The strange part is the power and fuel economy is better than ever! Just causing A stage 3 smog alert at every stop light

 

I have heard of some older engines getting thrown out of time and making great power clearing 10mpg, but it will crack pistons!