In the 2018 Impreza manual, it says for severe driving conditions, the front and rear differential oil should be changed every 15k miles with Subaru Extra MT 75w-80 which is what it came from the factory with. You can use Subaru High Performance SAE 75w-90 but it will detract from driveability and fuel efficiency. If the car never sees severe driving conditions, it says to simply inspect it every 30k with no mention of replacing it all the way through 132k.
I'd like to replace the front and rear diff oil every 50k miles. So I went to buy the Subaru Extra MT 75w-80 and it only comes in a 5 gallon bucket that cost $400. I went to the dealership, they told me they just use the 75w-90 in all the cars and offered to sell it by the quart. WTF...
I'd like to replace the front and rear diff oil every 50k miles. So I went to buy the Subaru Extra MT 75w-80 and it only comes in a 5 gallon bucket that cost $400. I went to the dealership, they told me they just use the 75w-90 in all the cars and offered to sell it by the quart. WTF...