On any ICE engine you are…
On any ICE engine you are going to get condensation, fuel dilution, combustion deposits and wear metals. I use a polyol Ester based synthetic lubricant same base lubricant used on jet engines. I let my vehicle sit all night and drain about 2 quarts every 3,000 miles. Many contaminates will settle to the bottom of the pan. Factory full flow oil filters are about 35 microns, not really enough to keep the lubricant clean. I also use a secondary 1 micron oil filter to remove particulates. I don't agree with any mfg on 10K oil changes, there is just too much going on. I doubt that Toyota uses a full synthetic lubricant. There is only one MFG out there that makes a lubricant that is Ester based for the automotive field and it is about $11.00 a quart. Thanks for Reading.