Corrosion inside rear differential housing?

Hello,
I drained and filled the rear diff on my 2022 Tacoma this afternoon. I noticed when looking in through the fill plug there was some corrosion inside. Fluid looked a lot better then I thought it would, minimal if anything on the drain plug magnet. No noises or issues present. Picture down below.

Did my 4Runner the other week and it was pretty spotless inside and that truck has a lot more miles and I remember doing the first drain and fill on it around 10,000-15,000 miles and it was near black.

Anyone with any insight or experience? This is my first Tacoma.

Thank you for your help,
Matt

 

Probably from sitting in the dealer lot for a while? Idk. I'm more perplexed why you changed the oil so soon. Truck isn't even a year old.

 

Document the age and miles, take pix in case later on there is an issue.
Rusty anything inside a semi sealed enclosure isnt great. Check the diff vent that it is working properly.

 

Moisture must have gotten in there in some way. Once saw a similar deal on a jeep differential after it did some deep water crossings. Long as the gear oil didn't look real milky i wouldn't worry. I wouldn't of replaced the oil till at least 30k miles.

 

My guess it was there before assembly.

 

Thank you for the replies. Truck was built in October of last year. Arrived at dealer in January and picked up a few days later.

I changed it out just from seeing how the first rear diff fluid changes looked on my current and previous 4Runners. I then have done every 30k on those two vehicles.

 

The rust is how you know it’s a genuine Toyota part. Toyota considers rust part of their corporate traditions.

 

I just hope toyota isn't charging us extra for it.