Hi Charles, I found this advice online for gearbox oil plus most, if not all, servicing requirements at:
http://www.geocities.ws/jeandebarsy/Servizio.htmlGEARBOX
Needs servicing every 10.000 kms or two years. I use 4.1 litres oil Esso XP COMPOUND EP 90. There's an oil filter element which should be cleaned, but it's hard to retrieve it without damaging it. Thanks to it's own oil pump, the gearbox lasts forever. A Flaminia gearbox is displayed at the Briggs Cunningham Museum in the USA....
To check the oil level, use the dipstick located on top of the gearbox. There's a removable plate in the trunkfloor to reach it.
From memory I couldn't find Esso XP COMPOUND EP 90, so bought Castrol Classic EP90 Mineral Based Multi-Purpose Extreme Pressure Oil, but yet to do the oil change. Again from memory 'Extreme Pressure' was the most important spec.
Chris