Pontiac 1958 Safari Owner's Manual page 42

FULL FLOW OIL FILTER- The full flow oil filter (optional at extra
cost)' is highly recommended for use on the Pontiac Engine. This
filter removes harmful particles of dirt, grit or other foreign material
befolle they can cause undue engine wear by imbedding theI»selves in
bearing surfaces or otherwise harmfully affect engine performance.
The filter element should be replaced once yearly or every 15,000
miles, whichever occurs first .
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