Originally Posted By: ARCOgraphite
Originally Posted By: Zaedock
If it was my truck, I would go one year and do a UOA. If it looked good, I would consider running that oil for two (2) years.
You are leaving all the sub 0.5" wear particulate in there, which is the main cause of engine wear. Why would you want to do that for the meager price of an OC? OK; 1x/year OCI on 2nd car w/low driven mileage; and 2x year min OCI on higher mileage cars especially in cold climates. Any other regimen will cause undue wear. All under the assumption that you want to keep the engine reasonably healthy for 250-300k.
The main cause of engine wear is startup/shutdown, not ".05" wear particulate".
A two year interval has already been done here by an individual with a 'Yota truck (IIRC) with NO issues. I've done multi year OCI on my trail Jeep which spends 90% of it's life as a yard tractor. No issues.
The main reason to run it two years is not to save money, it's because he can! Why change the oil if you don't have to? His engine will stay healthy, and at 8K miles a year, it will take him 37.5 years to reach 300,000 miles.