When comparing, at least in size to my ea82 oil filter, the newer subarus have oil filters that are 1/3 smaller...I have seen many auto manufactures go the same route with smaller filters regardless of the cylinders (4,6 or 8)...But Why??...are these newer smaller filters that much better?...Perhaps "my line" of thinking is not correct here, ..but if the filters were larger, couldn't the oil stay in longer

They are smaller, but they have more media surface area. Plus they may very well be using synthetic/glass filter media rather than the old tech cellulose. The newer media is more efficient as well.

 

Yes if you get a good glass media filter that has more filter surface area you could use it longer. Generally the glass media filters are recommended for 1 year max; cellulose 3-6 months max (because gasoline in the oil will deteroriate the media).

 

There's an article on EndWrench about this. Like the H6 filter can be used on the H4 but not the other way around. If you want i can see if I can find it.

I like the new filters. I think there is less pressure drop thru the filter. The front seals in my cars have been leaking less since I started to use the new ones. The size really doe not matter. It is what the filter element is made out of and how fine a filtration is done. Also the pressure drop thru the filter. The holes that you see in the bottom of the filter also effect the pressure drop. More hole area is less pressure drop epecialty whne it's cold out. That filter just sits out there in the freezing air.

Thanks, but I just found the article in the endwrech archives...

They are smaller, but they have more media surface area. Plus they may very well be using synthetic/glass filter media rather than the old tech cellulose. The newer media is more efficient as well.

 

Yes if you get a good glass media filter that has more filter surface area you could use it longer. Generally the glass media filters are recommended for 1 year max; cellulose 3-6 months max (because gasoline in the oil will deteroriate the media).

 

There's an article on EndWrench about this. Like the H6 filter can be used on the H4 but not the other way around. If you want i can see if I can find it.

Oil FIlters: H-4 Versus H-6 Engines

 

Also check out Filters: Excluding Undesirables

 

Oil Filters: H-4 Versus H-6 Engines

Subaru H-4 engines come from the factory with an OEM P/N 15208AA060

oil filter. The same part number is used for replacement. H-6 engines come

with an OEM P/N 15208AA031, and S0A5165109 is used as a replacement.

Both filters have the same physical dimensions as far as threads, O-ring, and

bypass valve opening pressure (23 p.s.i.) are concerned.

 

However, the H-4 filter has 141 square inches of filtration surface, while the H-6 filter has 201 square inches of filtration surface. The H-4 filter should not be used on the H-6 engine. Using the H-4 filter may cause it to become contaminated faster and allow the bypass valve to open, allowing unfiltered oil to circulate through the engine.