Ngl I was dead wrong about using synthetic oil in my old 7.3

Been running Rotella 15w40 conventional in my 97 F-350 for like 8 years. Buddy at the shop kept telling me to switch to full synthetic. I thought he was crazy, figured old diesels with high miles would just leak it all out. Finally tried it last oil change after he showed me his oil analysis numbers at 10k miles. Truck started easier in the cold this winter and I swear it's burning less oil between changes. Anyone else make the switch on a older motor and see a difference?

2 comments

2 Comments

amy_foster799d ago

Rotella is good oil dont get me wrong, but 15w40 conventional vs synthetic isnt really a fair comparison. 15w40 is a thicker base oil so it doesnt flow as well in cold weather. If you want to compare apples to apples you should run a 5w40 synthetic diesel oil like Rotella T6 or Delo 400. Itll still protect just as good at operating temp but flow way better when its below freezing. Also the whole "old diesels leak synthetic" thing is overblown. If your seals are already shot theyll leak conventional just as bad. Sounds like your truck is happy with the switch so thats what matters.

parkera229d agoMost Upvoted

My buddy made the switch to T6 in his 7.3 and swore his cold starts went from cranking for 5 seconds to firing right up. The old oil leak thing? Yeah his truck still weeps a LITTLE but it did that with conventional too.