Jeff:

You can run the vent back to the intake, I wouldn't change the oil %. It should not affect the mixture any amount, as the vented gases supposedly have all the free oxygen and fuel already burned. this will devrease your power though, by the amount the fresh air/fuel mixture is displaced with "Stack" gas. My opinion much better to run it into the exhaust, if there is a choice.

A new ring is an easy job in a Saito.

Bill.