Originally Posted By: Siv_EJ257
Oil has always been Subaru OEM 5W30 synthetic. I don't remember what group it is, but I do remember it's mixed for Subaru by a smaller company.
On the last oil service, the dealer switched to Mobil 1 5w30 synthetic, which has a terrible rep for killing bearings.
I think whatever killed the first block is what caused the sudden catastrophic oil loss.
Both the Subaru Idemitsu 5W-30 and regular Mobil1 5W-30 are thinner Resource Conserving oils. There have even been failures on Subaru filled WRX's serviced at dealers as well.
Whatever oil you decide on, do not use any Resource Conserving GF5 oil.
-Dennis