This really had me puzzled until I saw your other thread. Gutted for you. You must win with these bastards so good luck with it. Sorry though for not having the answer to your question.
Yes Dan the oil used in gearboxes is totally different to the oil used in you engine the grade and viscosity are different dont know if you can tell the difference out of the gearbox :idea: chemical analysis maybe
Stilo g/box oil is SAE 75 whereas engine oil is SAE 5w or 10w so someone would have to be very dim to put engine oil in the box
I've only ever read on here of 2 other Stilo boxes which have disintegrated.
If my memory serves me it seems that gearboxes that have been "worked on" seem more prone to wrecking themselves afterwards
Was this a new box or did they "repair" your bad synchro on the original box?