The 2.5 engine used in the Impreza and the larger cars, like the Legacy and Forester, is the same, right?

 

But, the oil filters are different. The same thread/pitch and gasket size, but the Impreza gets a teeny tiny cased one and the other cars with the same engine get the bigger cased one. Why? Why wouldn't Subaru just use the same filter on all the 2.5 liter engines.

 

The last oil filter I bought was the only one the dealer had, the larger one, but it fits the Impreza fine so I'm using it. Problems?

 

Just seems odd to me.

Up to 2002, all US 2.5L used the larger filter. Starting in 2003 with the Turbo model, the Turbo ONLY used the smaller filter so it would not be too close to the exhaust.

Then for 2004 it was recommended for all US 2.5L. The truth, the smaller filter has a larger filter surface and better filter capacity. It may be smaller, but built with different characteristics. Subaru of America is using all the older filters until they are gone and then will substitute the newer smaller one. Some parts stations only have the newer one.