I have an '04 Infiniti G35 6MT coupe, 97k miles, completely stock. I'd like to install a catch can to help diagnose and possibly reduce some oil consumption (Previous question with more details on oil consumption).
I'm losing 1 qt every 1400 miles. Never smokes blue or otherwise, runs smooth, pulls strong. I've tried Mobil1 5w30, Castrol Edge 0w30 and changing the PCV valve. Oil loss rate has remained steady. I've ruled out any external leaks.
I've seen a few ways this or other PCV modifications are done:
Sealed can between the PCV valve and the vacuum inlet on the manifold. This theoretically draws most of the nasty stuff out into the can and returns clean-ish vapours to the manifold. I expect this probably won't have much effect on consumption, but I'll be able to say, "yup, that's where my oil is going." The only potential problem I see with this is possibly a slight reduction in the vacuum on PCV (due to it having to travel through the can and additional plumbing), adding more stress to seals.
Pulling the PCV valve, plumbing it to a vented can intake, and plumbing the other side of the can to the fresh air inlet. The vacuum inlet on the manifold and fresh air outlet on the intake duct would be capped. This has reportedly seen some success in greatly reducing oil consumption, but having no vacuum on the PCV and only getting fresh-ish, unmetered air on the inlet seems like a potentially Bad Idea™.
Breather directly on the PCV port (no valve) and cap the vacuum port. Obviously, no vacuum and possibly changes the metering a bit. Still seems like an iffy idea.
What is generally the best setup for this? Are there other possibilities?