I’m a big fan of oil separators. My theory is if there’s less oil coming into the intake from the breather circuit, there’s less oil or gunk up the intake and get into the combustion chamber.

The best way to remove carbon IMHO is having an engine that burns clean. So I drive my engine clean by using a stock injector pop setting, stock timing and I limit oil vapor from getting back into the intake using a separator. I was chasing an engine shake and I finally concluded I had to reduce the oil vapor going into the intake.

Not so sure about diesels (that run lean Lambda) but on gas cars extra fuel or oil = more carbon deposit. If you get the mixtures back to normal the carbon will combust…slowly, eventually. It’s just simple thermodynamics you need excess oxygen to combust away carbon and it won’t happen with excess fuel. It has taken a couple of years for me to drive my SD clean. Before that I tried all kinds of solvent soaks and sprays without much luck. Once I stopped pouring a 1/4 cup of oil a month into my intake via the breather it has really transformed itself. But it didn’t happen overnight.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles