Subaru 2002 Legacy Owner's Manual page 401

It may be difficult to replace the spark plugs. It is recommended that you
have the spark plugs replaced by your SUBARU dealer.
The spark plugs should be replaced according to the maintenance
schedule in the "Warranty and Maintenance Booklet".
B Recommended spark plugs
2.5 liter models:
RC10YC4 (Champion)
BKR6E-11 (NGK)
BKR5E-11 (NGK)
3.0 liter models: PLFR6A-11 (NGK)
Maintenance and service
HBA004BA
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