[WHN]

Have used 20w-50 HD oil for years. Walmart.

Also, I add one 16oz bottle of blue STP.

Change once a year or 500 miles. Very rarely make the 500 miles.

Engine rebuilt in the late 60’s, has about 10,000 miles on rebuild. Does not use any oil and compression is all in the mid 60’s. Good power and very quite. Marvel Mystery Oil in gas.