I changed the original gearbox lube in BlackAdder last weekend at just 48k miles. Though 11 years old, it certainly wasn't as dark as what came out of MR BEAN at 80k. I drove it first to warm up the oil and stir any sediment, and let it drip good-n-long to get every bit out. As I had the rear end on jackstands but not the front, it may have accepted a little extra oil, so the full quart went in. MR BEAN has been running a full quart in the gearbox for nearly 50 k miles without a leak or other known issues, so he's getting the treatment next...