The best replacement for catch can is aos.

The best alternatives to catch can are rated as following:
★★★★★  aos
★★★★★  breather
★★★★  air oil separator
★★  breather filter
★★  pcv
★  cusco oil catch can

Your alternative for catch can is not listed? Suggest!
Speaking about catch can, one probably shouldn't forget about pcv.

Other search terms related to catch can and their ratings are:
★★★★★ pcv
You have in mind a companion for catch can and it is not yet here? Propose!



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catch can
aos
breather