Originally Posted By: HJC
Thanks for the welcome. My first engine had a spun rod bearing. Luckily I was on my last month of remaining warranty and Subaru gave me a new short block and turbo.
Well, I admit I was very ignorant of how hard turbo engines (especially modded) would be on oil. On the first engine's last months, I had Mobil 1 5W30 in there and assumed it would last me 6,000 miles of hard driving. Guess it didn't. Before that I use to change the oil every three months regardless of miliage. It also had a oil consumption problem. Something like 1/2qt every 1000 miles.
With the new engine, I'm sticking with thicker oils. Currently have RTS 5w-40 in the engine. No noticable consumption so far. I'm going to send that in after 3500 miles to see if that sodium is lowered.
I have looked at one of the Subaru forums within the past year. There is a history of some other WRX owners with spun rod bearings that used Mobil 1 5W30 and 10W30. Maybe it might be because:
1) It is a matter of the odds (such a high % of owners use Mobil
1 5W30 in those engines),
2) 3.1 HT/HS is not high enough in Mobil 1 5W30 for that engine
(engine power overmatches the oil).
3) Most of the other owners, that I read about, that spun rod bearings occured after sessions of hard cornering. Perhaps there was a lack of lubrication after pulling those high G's.
Either way, I would be using a thicker oil, like the Rotella 5W40, German Castrol 0W30 or Mobil 1 10W30 High Mileage.
I don't own a Subaru, maybe someone who does, can chime in or correct something that I have said.