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Am I the only one who thinks synthetic oil in older diesels is overhyped?
I know everyone swears by Rotella T6 for everything, but I put it in my '92 7.3L and started getting leaks at every seal. Switched back to conventional 15W-40 and it's been dry for 3 years now. Has anyone else had a similar experience or am I just lucky?
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blake4325mo ago
Whoa really? I mean, that sounds more like a coincidence than anything to me. Honestly, I ran T6 in my old 7.3 for years and never had any seal issues, and I've seen plenty of guys run it in way older trucks without problems. Maybe it's just me but I bet your leaks were more about old dried out seals finally giving up than the oil itself, especially if they were original to the truck. Conventional 15W-40 is fine and all but synthetic is just objectively better for cold starts and keeping sludge away in those old IDIs.
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finley_harris55mo ago
Spent three hours swearing at a seized bolt on my old 7.3 last weekend. Coincidence or not, I switched back to conventional 15W-40 and the drips stopped. Could be old seals giving up. Could be the synthetic just cleaned out decades of crud and found every weak spot. Either way, my concrete pad looks less like an oil spill now. So maybe the T6 is magic for some trucks. Mine just got offended.
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