Per 240Joe the economy comes from not changing the oil as frequently. If you run synthetic 3 times as long as Delo 400 then the price is a wash. Factor in your time and effort and you're ahead.

Your 616 might not care but in 60x engines with lots of miles the lash adjusters can get noisy. Synthetic oil can get them quiet again.

Sixto
93 300SD 3.0