Hello, i did say is messy at some point... and yes, is right mare sealing that sump ( i need to redo my one again, i can only assume was bent previously just a tiny bit) Your level sounds low to me. With engine cold, temperature that is outside ( around 20 celsius now) start engine apply brakes ( service and hand brake) move from park to drive, slowly release service brake (pedal) the hand brake should hold it not to slip fwd, cycle the leaver through pnrd and back about 2 minutes( make sure is not moving with hand brake on...) rest it in park or neutral with hand brake still firmly on. Open bonnet ( leave engine running) remove cap measure oil level, should be just under 20mm (18-19mm) at 25 celsius for maximum and 3mm for minimum... and this is cold level. On hot, the car needs to be driven from cold in gear till engine gets to operating temperature ( not parked till engine gets warm) when the temperature gauge gets to half that is 87-89 celsius mark transmission then will be 10 celsius lower... park on level ground, leave engine running and measure oil level again ( pay atention not to get burn or have clothing getting trapped in the fan as is dengerous) i used a long sleve jumper, thick one to be covered in order to remove cap at this stage. Gearbox oil on the dipstick should be 45-46mm for maximum and 30mm for minimum. Note the warm hot gearbox oil level is just for double checking that the first measurement on cold was right to begin with. Ideally you want to be as closest to maximum but not over and under no circumstances under minimum. This worked and prove pretty accurate now that i can read temperature transmission temperature i checked again and i could prove that is right. You have to know that transmission oil as it gets hot level is rising in the end it is a hidraulic oil...special atention needs to be paid to leaks on transmission as running low/dry will kill it so any leaks need to be put right. Hope this helps, As for tool to read temperature i have a few but only with the computer based one i could read the transmission temperature ( on top of all other 28 modules in this car, check the topic with the diagnostic last post) the other option would be probably a infrared temp reading tool or a probe based tool like fluke k temp but none are really justified to buy if only for this job. Checking gearbox oil on this is weird, as they could of simply put a dipstik in there with min max cold marks on one side and min max hot on the other side... i am in the process of making such a dipstik as getting the oil right for sure was a bit of a adventure first time till i concluded the above...