Thread: Oil choice for the 6.4
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Old 06-30-2009, 05:17 AM
Harley350 Harley350 is offline
Compression Ignition Addict
  

Join Date: May 2008
Posts: 305
Trust me SYN makes a difference in fuel mileage and engine longevity. It's a fact that has been proven many times. The only time you would not want to use SYN is during the break-in period.
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