Doesn't affect the oil as far as I know..and don't know about the atmosphere....in the case of my TTA (and the GN), it helps keep the crankcase pressure down so you don't blow seals.....so I figured the same principle probably applies to other engines as well. This is one of the basic mods to add to a Grand National or 20th Anniv TTA engine, but I don't know if the 3800 engines benefit in the same manner.

Hope this helps.