Subaru XT 1988 Service Manual page 270

2-4
ENGINE LUBRICATION SYSTEM
01 L PUMP CASE
Check the oil pump case for worn shaft hole, clogged oil
passage, worn rotor chamber, cracks, and other faults.
OIL SEAL
Check the oil seal lips for deformation, hardening, wear, etc.
and replace if defective.
12
ASSEMBLY AND INSTALLATION
Assembly and installation is in the reverse order of removal
procedure.
Observe the following:
1) Replace the a-ring and gaskets with a new one.
2) Coat rubber seal of oil filter with engine oil before
installing the oil filter.
3) Tighten oil filter an extra 2/3 turn after rubber seal
contacts pump case. Do not tighten excessively.