Check it hot after sitting for five or ten minutes, and make sure the car is level. Residential garage floors are rarely true level, they usually have some slope toward the overhead door for drainage. If you need to top it up Supertech Synthetic Blend 75W90 GL5 Gear Oil @ Wal Mart will work. I am running the Supertech Sythetic Blend gear oil right now, used it for my manual trans oil change and rear differential oil change. Feels the same as the factory oil as far as shifting goes. Anyhow, it would be a cost effective choice for topping up, compatible with all gear oils. Don't top up the manual transmission with any gear oil that contains Limited Slip friction modifiers. Some do, some don't.