I was dead set against those synthetic oil blends for years, then I tore down a 7.3 with 350k on one

Back in '08 my buddy kept telling me to run Rotella T5 in my 7.3 instead of the straight 15w-40 I always used. I figured it was just a way to charge more for half the petroleum. Fast forward to last spring, I had to pull the heads on a truck that had been on T5 since 150k. The valvetrain looked almost new, no varnish, no crusty buildup. The guy who owned it ran it hard too, hauling hay bales out of Cheyenne every summer. I still run conventional in my old 4BT but I've been using the blend in everything else for about a year now. Any of you guys had a similar experience where you changed your mind on something?

3 comments

3 Comments

jason_stone3mo ago

Honestly, what kind of tear down are we talking here? Was it a clean engine or did you just look at the valvetrain and call it a day? I've seen just as many clean valvetrains on conventional if the guy changes the oil every 3k miles. I had a buddy run T5 in his 6.0 from day one and it still had a weird sludge ring around the oil pan at 200k when he pulled it apart. Maybe it's just me, but I've never had a conventional oil fail me on any of my Powerstrokes. I'm still not convinced the extra cost is worth it unless you're pushing 30k miles between changes or something.

shane_nguyen3mo ago

Ngl you're spot on with that sludge ring thing. I tore down a 7.3 last year that had been on Rotella T5 its whole life with 250k on it and there was this weird crusty buildup along the oil pan gasket line that you just don't see on conventional oils if you stay on top of changes. My buddy's 6.0 has been on dino oil since day one, 5k changes like clockwork, and when we swapped the pan at 180k it looked brand new inside. Honestly I think these synthetics get hyped up too much for daily driver stuff. Unless you're running extended intervals or towing heavy in extreme heat, conventional does just fine. The cost difference adds up fast too, like 30 bucks more per change for what exactly?

lindareed2mo ago

That sludge ring thing is exactly what I've been noticing too. Did a tear down on a 6.4 that ran synthetic blend its whole life and there was this hard carbon crust along the pan rail that took a scraper to get off. Meanwhile, my old 7.3 that got cheap dino oil every 4,000 miles had a pan that looked like it was still break-in clean inside when I resealed it at 300k. The synthetic crowd loves to talk about detergents and base oils but if the conventional is getting changed regularly, the results speak for themselves at high mileage. Seen too many of these synthetic engines with weird sludge deposits in places the oil doesn't flow hard to justify double the cost.