Anyone consider the H4 opposed four 2.5 Subaru engine as rougher on oil than any other? Mine's a 2004 SOHC in an Outback wagon original spec 5W30 or 10W30 or 10W40 SL even all the way to 0 degrees F, believe it or not. It has 121K, new head gaskets, no leaks, with a very slight slap when cold that goes away quickly after a mile or two. It's been suggested these shear the conventional energy-conserving oils and may warrant HDEO. Sounds nutty to me, but it IS a different configuration. I like it ok, it works great, it kinda bounces around doing it's own thing under the hood, all the power of this engine is in low-RPM ranges but it does have an unrefined and rougher feel to it than the transverse DOHC four-cylinders in the Hyundais I used to drive. There are lots of them around, anyone ever do a UOA on one of these? Lord knows there are plenty of HDEO in 5W30 or 10W30 I could run in it, but I'd prefer, obviously to go PCMO 5W/30 Syn for 7500 OCIs. Thanks!