Triumph Repair: J overdrive, slow switch, gear oil

Question
What type of oil goes into the j overdrive? Does it have its own resevoir  or does it use the same oil as the gearbox?

Answer
Hi Jeffrey,
The OD uses the oil in the transmission. I don't know what kind of Triumph you have but most take gear oil and I have seen quotes from 70 weight on up to 90 weight gear oil.
But in practice I use to recommend 70 weight gear oil and if the shift in and out of OD was slow, switch to 20w-40 engine oil. As long as the seals were good I found it to work well.
Howard