[Xaxas]

Originally Posted by RWT

I'll join the hijack.

I don't have a dog in this fight but I do find it interesting. I personally wouldn't install a catch-can just because of the possible warranty issues. So for me the argument is purely academic.

Playing the devil's advocate, if oil/air separation isn't a issue why did GM patent a new two stage "Oil Separator Assembly" on December 11, 2018? They started using it sometime after patent application in 2016 (patent pending). My 2018 Colorado with the HFV6 LGZ engine had it, as does my 2020 Camaro RS with the HFV6 LGX engine. Both engines are naturally aspirated.

The article says the new two stage Oil Separator Assembly, "can alleviate pre-ignition due to oil in the combustion chamber"...It does not say anything, however, about carbon build up on valves. The actual patent refers to the presence of oil in the combustion chamber and pre-ignition relationship as hypothetical. Again, no mention of carbon build up on valves. See both the article and the patent below.

The article:
https://gmauthority.com/blog/2019/01...ator-assembly/


The Patent:
https://gmauthority.com/blog/wp-cont...2019-USPTO.pdf



No expertise implied or expressed

Thanks for sharing this, I will def give it a read, but it's clear GM is trying to alleviate the blowby issue in a way that doesn't really require maintenance, could be a result of newer engines having turbos and high compression ratios, everyone heralded DI as the best thing for tuning, performance and efficiency, now you're seeing automakers going back to adding PI and combining it with DI, guess they know something we don't after years of data (and complaints)?

I also think there's a certain not liked German automaker who we have to thank for shedding light into this issue.