I suppose if I get 20 answers, I’ll get 20
different opinions. But here goes:
2007 Outback XT with stock motor, (but not stock suspension) has had a steady diet of Castrol for 50k+ miles: mostly 0w30 Euro Edge A3B4, but recently a mix of 0w30 and 0w40, which are supposedly quite similar, so I thought extra mixable…given that 0w30 is hard to get, vs 0w40 readily available at Walmart. Now at 150k, and sweating bullets something is about to go. Original head gaskets, and original turbo. More stop & go than highway. But occasional misbehaving. FYI, this engine did not like Pennzoil Platinum, though that was a long time ago (90K ago…first change after buying used at 52k. For 60k-95k mostly used Mobil1 5w30 ( with maybe ~20% 0w40 mixed in, thinking that would be more stout than the straight M1), followed by the last 50k or so of Castrol.
several possibilities, help me choose (or confuse me further):
1) step up to straight Castro Euro Edge 0w40, which will be thickest oil ever used in this engine (vs 50-50% mix 0w30 and 0w40 last 2 fills)
2) pay Amsoil-like pricing for maybe the last remaining case of 0w30 Euro Edge in the area. Could just be me, but I think engine likes this oil.
3) step sideways to Mobil 1 FS Euro 0w40, which again would be thicker like #1.
4) use Amsoil SS 5w30 which I bought for my other vehicle; this would be the thinnest / lowest HTHS oil this engine has seen in a long time…maybe since the Pennzoil
@56k. The good news is it’s “free” for now, but I worry about such a thin oil in this “thickie-loving” engine design, plus probably better suited for the Ford EB, and I’d probably choose something equally pricey for the Ford since long summer intervals for it are my preference.
I really did think the Castrol Euro (German then Belgium) 0w30 was ideal with virgin KV100 above 12 and HTHS 3.5 or so, and plenty of PAO, though surely newer oils have improved??? All the chatter about HPL and cleaning has made me question most all my previous thinking, but my UOA’s with the Castrol were dam*d good. I plan to do UOA again this time.