Oil Filter comparisons - EJ25 vs FB25 vs Ryco

[Yowie]

Executive Summary

Do not use Ryco oil filters - the bypass valve spring is too weak.

An FB25 oil filter appears to be the same as an EJ25 oil filter other than being longer with more filter media. I recommend using FB25 filters.

Mazda RX8 filters are sometimes held up as an option. I haven't tried one at this point, but if I get my hands on one I'll use it, cut it open and then add to this thread.

Likewise, no experience with the pink STI filters.


Chop Chop

There is lots of rumour and chat about oil filters. Cutting them open tells you a lot. This type of tool is good, because you don't contaminate the filter bits inside with shavings from your hacksaw or angle grinder (and you don't make a huge mess and don't end up in hospital from a mishap with a sharp slippery filter):-



To reduce mess pre-cutting, press the rubber (?) anti drain-back valve with a thin stick via one of the many small holes to drain out most of the oil on the dirty side of the filter media.


Oil filter parts



Left to right there is:-

(a) the threaded base-plate that mates up to the engine (underside shown here);

(b) anti drain-back valve;

(c) filter media canister;

(d) base spring (bottom of picture) that sits in the dome-end and presses the filter media canister up against the threaded base-plate; and

(e) steel body of filter.

[Yowie]

EJ25 vs FB25 oil filters






Above are the filter media canisters of the EJ25 (short) and FB25 (long) oil filters side by side.

From handling both filters, it seems to me that the two filters are identical but for the additional length of the FB25 filter. Specifically:-

(a) same thread

(b) same diameter (body and rubber seal ring)

(c) same base spring

(d) same filter media type and filter media canister construction; and

(e) crucially - same bypass valve pressure as far as I can tell from pressing on both.



Bypass valve?



This little button at the dome-end of the filter media canister is spring loaded.




Here is a chopped-open version from a clean Ryco filter (discussed below).


The way the filter works in ideal conditions is:-

(i) "dirty" oil drawn from the sump enters the many small holes in the base plate (pushing the anti-drain-back valve out of the way as it enters) and moves to the outer perimeter of the filter body;

(ii) oil moves through the convoluted cardboard that makes up the filter media into the centre of the filter;

(iii) newly clean oil flows up into the engine through the large central hole.



Above is a picture of the filter media cut away from the cartridge.



Unfortunately, when conditions like "cold start", "oil too thick" ,"revs & oil pressure too high" and/or "filter media too clogged with rubbish" apply, the oil flow trying to get through the filter media is not enough for what the engine requires. Faced with the choice between "engine starved of oil and big-end bearings seize" or "allow some dirty oil through into the engine", the designers choose the latter.

Under those conditions the pressure on the dirty side of the filter pushes against the Bypass valve, the spring pressure is overcome and some dirty oil enters the centre of the canister from the dome end of the filter.

The dome end of the filter faces downwards on an EJ25. sludge and bits tend to collect there. Opening the bypass valve to let in oil sitting where the sludge & bits lurk is not ideal.. We want to reduce that occurrence.

Here is some dome-end sludge:-

[Yowie]

What about Ryco filters?

I have cut open two Ryco filter types:-

(a) their EJ25 filter equivalent (Z436); and

(b) what I assume is their FB25 filter equivalent (Z411) - more specifically the Z411ST which is their finer filter media premium product.




Left-right in the image below are the cartridges out of a standard EJ25 filter, the Ryco Z436 and the Ryco Z411ST.



As you can see, the height of the filter cartridge for the Ryco Z436 is shorter than the EJ25 equivalent.

The Ryco Z411ST filter cartridge is the same height as the FB25 filter cartridge (not shown above but I measured them).

Of minor interest, Ryco use a coil spring (not a plate of spring steel) to hold the cartridge against the threaded base plate.

Of greatest significance is the fact that the Ryco bypass valve spring pressure is significantly weaker than the OEM Subaru oil filter bypass valve spring pressure.

In other words, all things being equal, the bypass valve will crack open earlier on a Ryco filter to let in unfiltered oil (etc.) more often / earlier / etc.

That is a deal-killer to me. It's a shame, because I wanted the large-body Z411ST finer filter media (as advertised) premium Ryco product to work out for me.

As such, based on the evidence to hand, I recommend:-

(a) not using Ryco filters;

(b) using an OEM FB25 oil filter on your EJ25 (assuming no clearance issues for a longer filter body) rather than an OEM EJ25 filter because:-

(i) there is more filter media;

(ii) in theory, it will take "worse" non-ideal conditions to cause the bypass valve to crack open because the larger filter media area has more flow capacity;

(iii) you have a tiny bit more total volume of oil in the sump-filter-engine loop without raising the level in the sump (with associated problems of that). Probably an insignificant difference, but it's something;

(iv) parts, construction, valve spring pressure, etc. is all the same as an OEM EJ25 filter (as best as I can tell) apart from more length.

[LibertyTragic]

Awesome post Yowie. Was this the product of Corona isolation and boredom?

Interesting findings on the bypass valve!

Thought I'd share this vid from a Subaru mechanic youtuber I follow. An hours worth of various brand filter opening for the EJ255:

[Turbo Lag]

Great informative post. I've always heard genuine is best but haven't seen any actual information to back this up until now. Guessing 15208aa160 is the part number for the FB25 filter? I'll give this a go next time I do an oil change.

[Yowie]

Awesome post Yowie. Was this the product of Corona isolation and boredom?

Interesting findings on the bypass valve!

Thought I'd share this vid from a Subaru mechanic youtuber I follow. An hours worth of various brand filter opening for the EJ255:

Thanks Liberty Tragic. Some of the pics and comparison were from a while back (the Ryco v EJ25 stuff). The FB25 photos etc come from yesterday - my first oil change after using an FB25 filter for the first time. I was pretty keen to chop it open to see if the bypass valve pressure was the same but too stingy to cut open a clean one. ("I ALSO like to live dangerously").

Time permitting I tend to cut open my filters after an oil change to see if there are any shocking collections of visible metal shavings. I also send oil samples to a lab from time to time for what that's worth (not gospel, but indicative).

I think I saw that oil filter youtube video (and now youtube thinks I want to see more videos of oil filters FFS!). The poor build quality of those blue USA "genuine Subaru oil filters" is a bit of a shocker.

Great informative post. I've always heard genuine is best but haven't seen any actual information to back this up until now. Guessing 15208aa160 is the part number for the FB25 filter? I'll give this a go next time I do an oil change.

Cheers Turbo Lag. I was stubborn enough to reject the "genuine is best" idea until I started cutting them open. Correct - 15208AA160 is the part number for the FB25 filter.

[norbs]

I've always used stock filters. That and coolant.

Excellent write up by the way !!

[Yowie]

Cheers Norbs.

Over the years i've tried to figure out where OEM is best versus when aftermarket substitutes are as good or better. It's a long journey

[fedaykin]

Great post. Thank you for sharing.

[Turbo Lag]

Put my money where my mouth is. Thankfully it still fits nicely with my sandwich plate as well. It comes down to about the same level as the oil drain.

[Yowie]

Is that a water-to-oil cooler, then a sandwich place, then a tall oil filter?

I don't know if you'll win "lowest hanging oil filter" but you'll make the finals!

[Turbo Lag]

Haha just factory mounting point, no change from stock! Only the sandwich plate is my addition. It is rather low but I figure since the oil drain has never impacted (even with undertrays off on all my cars to test), don't see why this would either. Plenty of the normal oil filters lying around just in case though. Guess yours would be a bit different being in a Foz.

[Yowie]

The Forester doesn't come with the oil-to-water cooler, so regular or long filters are still higher than the bottom of the exhaust manifold heat shields.








If your car does 100% on-road driving then I don't see any issue with the height you're running there. If you sign up for a dirt track rally day it might be worth switching to a regular filter for the day so you don't tempt Murphy.

With one eye on large rock impact risk I cut down my "with spout" fumoto oil drain valve to "without spout" with a hacksaw after I put the Forester on lowered (i.e "regular car height") springs.

[Duck!]

Where'd you get the suggestion of the Z436 as an equivalent filter from? Everything I've seen lists the Z495 as the compatible filter for the EJ25.

[Yowie]

Where'd you get the suggestion of the Z436 as an equivalent filter from? Everything I've seen lists the Z495 as the compatible filter for the EJ25.

The Ryco website. Eg https://www.rycofilters.com.au/Search/S ... 009&liter=

I can't find much on the Z495 at first instance, but this https://www.rycofilters.com.au/catalogu ... /part/Z495 shows that it does not have an anti-drain-back valve, which seems daft for a bottom-of-engine mounted filter. Eg your oil galleries would have all of the oil drain out of them while the engine is switched off, so the next start would be much harder on all of the wearing surfaces.

On what basis do you say that a Z495 is a Subaru-engine filter?