My 2002 ls430 transmission oil has been leaking excessively for the past week. The leak have been going on for months now. The dealer claims it’s the front oil pump has gone bad. I filled it with 2 quarts of oil just now and it continues to leak heavy even after running for only 2 minutes. What part would I need to change and how easy would it be to find? Gonna take it to another shop on the weekend. Until then and until I can actually fix it can I drive it but add transmission fluid to prevent it from running low?

The front pump will not cause a leak by itself. If it has play due to worn bearings it could cause the seal to leak.

Does it leak while running or while it is shut off? How many miles on the tranny? Is it making a loud whining noise?

Where is the fluid coming from? The front in between the trans and engine or is it the trans pan. Maybe some pics would help.

Take it to another shop to get a second opinion. It could be an ATF line that is relatively easy to replace, or a front seal that can be a PIA. If the leak started rather abruptly, I’d suspect a ruptured line. Maybe a rubber hose connecting to the radiator.

The transmission has 93k miles on it and it leaks while running. The leak is coming front the front of the car.

The front of the car or the front of the trans? If coming from the front of the car it could be a transmission line or transmission cooler. If from the front of the trans it may be the front seal for the torque converter.

Find the leak and take a photo to post. Many folks here can help troubleshoot.

Take it to a transmission shop for a second opinion. If it's leaking between the engine and trans it's most likely the torque converter seal. If it's in the front of the car it's a cooler line or the cooler itself.

Can I still drive the car and add atf to it once the level is low?

I personally would not drive it. That is a bad leak and the fluid is on the exhaust. If it is working and fluid is running out the pump is working.

So that would mean that the dealer would be wrong. What other thing would cause it to leak it had the p0770 code

It could possibly be a worn pump (shaft play / wobble) causing the seal to leak. Unless it has been worked on before or abused, I have not seen a toyota/lexus pump go out under 100k miles. I have not seen the car, but when a trans pump goes out the car does not move well, or at all. the p0770 code is usually a shift solenoid malfunction.

that’s the thing the car moves only when it’s filled with oil and the oil usually empties out at a fast rate

What trans oil should other than Toyota certified oil?