1999 Tacoma Wal-Mart ST Full Synthetic 5w30 total miles 185,400 at time of sample, comments are due to my inquiry if the oil was breaking down in service, friends truck. Back story, had the valve cover off about 20,000 miles ago for a gasket change and noted lots of old hard carbon deposits in the engine. He's owned the truck since it had 80,000 miles, we suspect the previous owner was slacking on oci as all the seals and rubber gaskets are hard as a rock. Truck has been serviced with ST Full Syn at roughly 5,000 oci for the past 105,000 mi. Oil filter cut revealed the bottom 1/3 or all pleats completely impacted with hard carbon deposits. Since this sample was done 2 more have been done one with ST Full syn and a dose of seafoam in the oil to try and clean it out and the same fram filter with no noted carbon, and one more oil change with PUP without a filter cut using a Wix Gold 1515 filter for its extra capacity. Not sure what caused the random burst of [censored] but truck is still running exceptional at 195,000 mi.