I spoke with the lab tech at Blackstone about the diff today. He said the results could be from of a combination of heavy early use from extensive racing back in the day, combined with subsequent surface rust from 25 years of storage since these diffs have an open air valve at the top that can let in moisture. He recommended driving it a few miles and then flushing it again, maybe with a good internal soaking with solvent and let it sit, then drain it fully again and hose it out with a couple cans of brake clean. Then refill with fresh 75W140 and additive and drive it. Then sample in a hundred miles. If it comes back as fresh oil with no contaminants it may be good. Versus it showing new iron contamination at a similar level, then its time to swap out the diff and perform an autopsy.
Last edited by njsteve; 11-01-2022 at 04:25 PM.
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