Triumph Repair: gearbox fluid, synthetic products, gear oil

Question
Hi,
I have my spitfire pulled apart, and the body parts are coming back from the shop in the next week, so she'll be ready to reassemble.  While the transmission is exposed I'd like to change the lubricant in it, and have always used synthetic products in my vehicles.  Can you tell me specifically what kind of lubricant goes in the manual transmission.   Do you agree with the preference of synthetics?  And if you can tell me what you run in your spitfire that would be great as well.
Thanks for your time,
Eric

Answer
Hi Eric,
I don't have any experience with synthetic oils in the gearbox. BLM suggests 90w gear oil, however, I like to use a lighter oil than that and if the syncros get worn and start clashing gears I like to go to engine oil in Triumphs and MGs. Especially in cold weather.

I have just now started to use synthetic oil in engines and will have to "wait and see" on that because over the years I have learned to distrust manufactures claims on anything. Too much of their hype is based on lies and half truths.
Howard