Rod bearing failure is common with Subaru Motors. The new FA series even more so than the older EJ series. FA motors are failing at stock power levels. Even mild upgrades require a built motor.
Bearing failure can occur on any motor, at any time, with any oil. The best prevention is to make a properly built motor a priority. Get it right and your motor will last.
Build quality matters more than the oil your use. Proper clearances during the build will prevent bearing failure better than anything else. Stock bearings with proper clearances will last longer than race bearings with bad clearances.
- Avoiding detonation or knock will also prevent bearing failures.
Proper procedures must be used during the rebuild of a rod bearing failure. The failed bearing contaminates the oil with metal debris.
The debris flows with the oil into every part of the motor. There are certain items that are not serviceable or cannot be properly cleaned, these must all be replaced. Oil pumps, Variable Cam Gears, Oil Coolers, Etc... Miss one of these and you are headed to another failure.
Anything that touches the oil needs to be carefully inspected. If an engine is run too long with contaminated oil, it can become a total loss.
Spend money on a properly built motor to prevent failures down the road. Make sure the shop doing the rebuild is familiar with the procedures that need to be taken to prevent a secondary failure.
A failure often seen is caused by contaminated oil getting into the new motor, get it right, make it last.