Listers, What is the advantage of synthetic oil over conventional in a differential, manual transmission, or similar mechanism, as opposed to in an engine where the ability to suspend combustion byproducts is critical? Is it just that the synthetic is less viscous when cold, or is it likely to decrease friction and wear significantly over the whole operating temperature range? Or something else? Does anybody have any anecdotal evidence from M-Bs or anything else of, say, differentials appearing to last longer because they had Mobil 1 in them?
I'm asking because I need to change the oil in the front and rear differentials, transfer case, and manual transmission in my Isuzu (supposed to be done every 30K and who knows when the moron PO did it last), and I'm trying to decide whether to just put any old thing in there or spring for all Mobil 1 products. (5W30 is specified for the tranny and transfer case, and 80W90 for the diffs. The rear diff is limited-slip.) Alex Chamberlain '87 300D Turbo '93 Isuzu Trooper
