How much oil is too much in the LMM turbo mouthpiece?

[ColdTolerant]

Popped my intake off today and the turbo mouthpiece was coated in oil. I know the PCV system dumps back into the intake, but how bad is this for the intercooler long-term? Are most of you running a PCV reroute kit, or is the mess just something we have to live with to stay street-legal? I’m tired of cleaning oily residue off my boots.

 

[HeavyMilled]

The oil you’re seeing is a classic LMM "feature" caused by the PCV system venting crankcase gases directly into the turbo inlet. While a light coating is normal, excessive oil eventually pools in the intercooler, degrading the rubber boots and causing them to "sweat" or blow off under boost.

How long are you willing to keep cleaning that mess? Most owners consider a PCV reroute the single best mod for intake longevity. It keeps the intercooler and turbo vanes dry, preventing that oily sludge from baking onto your components. If you need to stay street-legal, an oil catch can is a great middle ground.

What does your intake look like? Is it just a film, or is there standing oil?

 

[CanyonCrawler]

If you can see a puddle forming at the bottom of the mouthpiece, it’s too much. How bad is it for the intercooler? Over time, that oil mist coats the internal fins and kills your cooling efficiency. Even worse, it softens your rubber boots until they eventually pop under boost. I got tired of the mess and did a PCV reroute years ago. It’s the single best mod you can do to keep your top end clean.

 

[RawCast]

If you see a puddle sitting at the bottom of the mouthpiece, it’s already too much. How bad is it? Over time, that oil mist coats the internal fins of your intercooler, which kills heat exchange efficiency. Even worse, the oil degrades the rubber boots until they eventually blow off under boost. A PCV Reroute is basically mandatory if you want to keep your intake tract dry and your turbo vanes from gumming up.

 

[RoughCut_Ed]

How much do you value a clean engine versus being 100% street-legal? Technically, a reroute isn't 'emissions compliant' in some states, but it’s the only way to stop the mess. Most guys run a 'stealth' reroute that vents down the frame rail. Whatever you do, don't just leave it. That oil eventually finds its way into the intercooler boots and makes them slip off constantly.

 

[FixedPivot]

If you see a puddle forming at the bottom of the mouthpiece, it’s already too much. How bad is it for the intercooler? Over time, that oil mist coats the internal cooling fins and acts as an insulator, killing your heat exchange efficiency. Even worse, it softens your rubber intercooler boots until they eventually pop off under boost. A PCV reroute is the only way to keep your intake tract bone-dry.