For my next oil change I'm going to give in to some advertising hype, lol. I'm going to use Pennzoil yellow bottle 5W30. After all, according to a statement on Pennzoil's web site, 7 our of 10 drivers percieved their cars to run better after a Pennzoil oil change. Seriously, I'm using Mobil Clean 5000 right now and want to switch to a different conventional and YB is probably going to be it. Can't go wrong with YB, and being a naturally aspirated Subaru there is no need for synthetic. Why am I switching? I'm trying to get that sewing machine quietness back into the engine that it had on the factory fill. Since putting in the MC5000 there is a little bit more mechanical noise... not much but I can tell a slight difference. I'm hoping the YB will quiet it a little. My old school '94 Dodge Dakota 5.2 V8 has always been quietest when running on YB. Just changed the Dak out from O'Reilly store brand 5W30 to YB 5W30 at the last oil change and the valve train is a little quieter... same brand and p/n oil filter for both fills, so I'm thinking its good old YB working its magic.