UPDATE
Just received UOA from my latest OC;
7,371 mi. on sample/ 151 hrs.
178,884 mi. total on truck
sample date 7/12/13
John Deere Plus 50 II 10w-30 CJ-4
Oil & Filter changed at the time of sample
Sampling lab is OILSCAN (Deere)
iron........................14
chromium.....................1
nickel......................<1
aluminum.....................4
lead.........................5
copper.......................2
tin..........................1
silver,,,,,,,,,,,,,,,,,,,,<0.1
titanium....................<1
silicon......................7
boron......................316
sodium.......................1
potassium..................,10
molybdenum.................311
phosphorus................1056
zinc......................1264
calcium...................1558
barium.....................,10
magnesium..................953
antimony...................<30
vanadium....................<1
viscosity @100C...........10.4
fuel......................<.50
T/S % vol....................1
Just posting to keep everyone updated, nothing out of the ordinary for this truck/oil for 100,000 mi. since switching to 10w-30. I bought this truck new in '07 and switched to 10w-30 several years ago.