Your question is confusing. An A/T does not use gear oil, it uses A/T fluid. Some manual transmissions do use A/T fluid but I know of A/T that uses gear oil. But the answer is the same for both manual and A/T. You add fluid at the same place you check the fluid level.
for starters....is it manual or automatic,,,,big difference......on a manual,,,you have to get under the car to to the gearbox,,,,,then find the gearbox plug bolt,,,then fill the gearbox to that level....automatic is very different
You fill it through the dipstick hole.
To fill up the automatic transmission fluid on a Peugeot 407 with a 4-speed automatic gearbox, first ensure the vehicle is level and warm. Locate the transmission dipstick or fill plug, usually found near the back of the engine bay. Using a funnel, add the recommended type of automatic transmission fluid through the dipstick tube or fill plug until it reaches the appropriate level on the dipstick. Finally, check for any leaks and ensure the fluid is at the correct temperature during the check.
On a 1996 Ford Mustang : The automatic transmission fluid level dipstick is located in the engine compartment , near the firewall , on the passenger side of the engine in the engine compartment ( use a funnel )
Through the check/fill plug in the center of drain plug
On a 2005 Ford Mustang GT the automatic transmission does not have an automatic transmission fluid level dipstick ( and the manual transmission fluid level is checked underneath the vehicle at the transmission fill plug )
To check the oil in a 2006 Ford Fiesta Duratec semi-automatic gearbox, start by ensuring the vehicle is on a level surface and the engine is warm. Locate the gearbox dipstick or fill plug, usually found on the side of the transmission. Remove the dipstick; the oil level should be within the marked range. If it’s low, add the appropriate transmission fluid through the fill plug until it reaches the correct level.
To change the automatic gearbox oil in a Peugeot 407, start by ensuring the vehicle is on a level surface and using jack stands for safety. Remove the drain plug to let the old oil drain out completely, then replace the plug. Next, fill the gearbox with new oil through the dipstick tube or designated fill port, using the recommended type of oil for your model. Finally, check the oil level with the engine running and adjust as necessary.
Take the wheel off closest to the gearbox, then you can clearly see the Automatic Transmission fluid drain plug. Its just behind the brake caliper. You may want to fill up and drain the gearbox twice in order to properly flush the gearbox as best as possible.
You can top off the oil in the gearbox on a 206 Zest by removing the fill plug on the top of the gearbox and using a funnel to fill with oil.
Okay- Do not put automatic transmission fluid in a manual transmission! You need to put gear oil in a manual transmission. This is usually brown like oil and about 90 weight. Fill gearbox until the level is up to the fill hole but not flowing from the fill hole(as the fill hole is on the side of the gearbox).
how do I fill the gearbox oil on a vauxhall vectra