The Sienna engine is very efficient, just look at the tailpipe, seeing Siennas passing by, I can see clean inside tailpipe.
Pulling out the dipstick on a 2004 to 2018 the oil will look clean, even after 10,000 miles.
These engines NEVER wear out, they don't contaminate the oil, they don't burn much oil and will only die if you lose radiator water or the idiot forgot to put oil in the engine.
With most synthetic oils, you will burn more because the oil viscosity is a lot lower. The only reason for synthetic oil is for fuel economy. Seen inside of 100k engine, and they look perfect.