Subaru o/f drainage-mess

[Nayov]

On a late model subbie with the o/f mounted on top (base down, too) where does the oil drain?
It always leaves a pool of oil when changed, yet when they come in for an o/c the area is always dry.
A coworker insists in drains into the engine. Another said it drains out to the environment.

First pic, the typical pooling. Second, cleaned out w/ a rag. At 8 o'clock there looks to be a drain hole...into the engine, though?

 

[The Critic]

Unscrew 1/2 turn. Lift vehicle to drain oil and rotate tires. When those two items are complete, lower vehicle and slowly unscrew the filter.

Basically the filter needs time to drain, but in order to do so, loosen it a little first.

 

[Donald]

The question the OP asked has been a curiosity item for me also. The area between where the oil filter seals and the outer edge of the filter base housing can hold a little oil and there is a hole for it to drain into. Where does that hole go? Cannot imagine they drain it on the ground and draining it back into the engine would mean that any dirt in that area would also be drained into the engine. Could include water from washing down the engine bay.

 

[Blagoje]

Another said it drains out to the environment.

I really want to hear the explanation as to how anyone could come to that conclusion.

 

[Wrenchturner44]

I really want to hear the explanation as to how anyone could come to that conclusion.

Ok, I will take a shot. Out of ignorance they probably associate the oil filter drain as the same as the overflow tube on the radiator cap outlet.....it drains to the open environment in most cases.....yes I know......antifreeze has way different contaminating properties vs that of motor oil.

 

[JohnnyG]

It goes back into the block. There will be some left in the filter for a while until it "bleeds" through the filter media, if ever. Provided the ADBV is working correctly that is.
Once this filter is filled back up from starting the car, it won't drain back unless air is allowed to enter the filter.
The cartridge type filters are the same. They stay full when sealed, then when opened for replacement, they quickly drain back into the oil pan.
This is one drawback (or benefit, depending on your viewpoint) of doing "top side" oil changes. If that cover isn't at least cracked a little bit, that oil will remain in that assembly.

 

[ARCOgraphite]

Ok, I will take a shot. Out of ignorance they probably associate the oil filter drain as the same as the overflow tube on the radiator cap outlet.....it drains to the open environment in most cases.....yes I know......antifreeze has way different contaminating properties vs that of motor oil.

Subaru owner of multiple FB over the years. The filter mount "Drain" is not drilled. It goes no where.
center tube is to engine the hole in the "moat" is from up from the oil pump.

Before an OC, I let the car sit an hour after a hot shut off and - the filter is empty.
Clean the around around the filter base of dirt and grit BEFORE removing. Slowly un-screw the filter.
Voila !

Otherwise, in a rush, see post #2 by The Critic.

And yes, it not a great design. Especially given filter is empty at every start after a short sit!
- Ken

 

[Addicted2jeepz]

I think some are misunderstanding the OP's question, or maybe I am

He is referring to the hole that I circled, it's outside the oil filter seal surface. It collects dirt and debris and is open to the atmosphere all day long, there's no way that goes back into the engine...

 

[JohnnyG]

Well, you're right there!
I've never seen such a stupid design. What purpose can this possibly serve?

 

[WagonWheel]

I just changed the oil for the first time on my daughter’s ‘17 Legacy 2.5i with ~ 101k mi. There was no pooling in the filter housing when I removed the o/f.

However, there was a bit of a mess from the oil draining from the drain plug and flowing back into the plastic shield. I had it on front jack stands. I think next time I’ll lower it when pulling the plug.

 

[bobdoo]

On my Impreza, it was an inverted nipple/depression with no drain hole. I wiped the oil catch cup clean before removing the filter, and again after installing the new filter (to catch the oil leaked out of the old filter).

 

[Accent Abuser]

Unscrew 1/2 turn. Lift vehicle to drain oil and rotate tires. When those two items are complete, lower vehicle and slowly unscrew the filter.

Basically the filter needs time to drain, but in order to do so, loosen it a little first.

Yup this is what I do.

 

[ARCOgraphite]

I think some are misunderstanding the OP's question, or maybe I am

He is referring to the hole that I circled, it's outside the oil filter seal surface. It collects dirt and debris and is open to the atmosphere all day long, there's no way that goes back into the engine...View attachment 98993

That is the outer catch basin drain that is not drilled from the factory
Maybe it is in some markets with a hose to the ground.

There is a nipple under that drian hole on some engines, I haven't look at our 2021 FB25.

We have owned 4 subarus with FB motors so far, Never seen one with the drain drilled.

 

[ARCOgraphite]

Well, you're right there!
I've never seen such a stupid design. What purpose can this possibly serve?

Drain water out of the catch cup if drilled - but then it wouldn't work to catch leaking oil .

Maybe to catch some weeping or a mess when removing the filter to quickly.

Never seen weeping with the P-ring base gaskets.

 

[BHopkins]

The first few oil changes on my wife's Outback, I ended up with oil inside the catch tray, after removing the oil filter. It did not go anywhere until I carefully cleaned it up with a paper shop towel.

As The Critic has mentioned, this condition can be entirely avoided by changing sequence of oil change steps. Drain the motor oil. Remove the oil fill cap. Remove the oil filter only after the oil has been drained. By following this sequence, almost no oil, if not none at all, will overflow into the catch tray.

Another hint. Clean the oil filter catch tray area with a shop towel and compressed air before removing the oil filter. This reduces the risk of getting dirt into the engine.

 

[Donald]

The first few oil changes on my wife's Outback, I ended up with oil inside the catch tray, after removing the oil filter. It did not go anywhere until I carefully cleaned it up with a paper shop towel.

As The Critic has mentioned, this condition can be entirely avoided by changing sequence of oil change steps. Drain the motor oil. Remove the oil fill cap. Remove the oil filter only after the oil has been drained. By following this sequence, almost no oil, if not none at all, will overflow into the catch tray.

Another hint. Clean the oil filter catch tray area with a shop towel and compressed air before removing the oil filter. This reduces the risk of getting dirt into the engine.

Does the filter have an ADBV? I thought it did?

An ADBV should keep the filter full of oil. That is the point.

 

[BHopkins]

Does the filter have an ADBV? I thought it did?

An ADBV should keep the filter full of oil. That is the point.

All the filters I have used have an ADBV. I've used the Subaru 152058AA15A, the Fram Ultra, the M1, and the NAPA Gold.

Since the ADBV does nothing to keep the filtered oil, in the center of the filter, inside the filter, it will drain out when the filter is removed. This is what will drain back into the engine, if you drain the oil first.

 

[Donald]

All the filters I have used have an ADBV. I've used the Subaru 152058AA15A, the Fram Ultra, the M1, and the NAPA Gold.

Since the ADBV does nothing to keep the filtered oil, in the center of the filter, inside the filter, it will drain out when the filter is removed. This is what will drain back into the engine, if you drain the oil first.

With the engine off there is 5 QTs in the sump. Probably room for 6 QTs.

When I turn the engine off the oil in the filter does not drain back into the sump. But drain the 5 QTs from the sump and the oil will drain back out of the filter. How does the filter know if there is any oil in the sump?

 

[BHopkins]

With the engine off there is 5 QTs in the sump. Probably room for 6 QTs.

When I turn the engine off the oil in the filter does not drain back into the sump. But drain the 5 QTs from the sump and the oil will drain back out of the filter. How does the filter know if there is any oil in the sump?

I couldn't tell you. All I know is that when I did my first few oil changes on the FB25, I would sometimes take the filter off first. When I did, I ended up with oil running out of the filter and into the catch basin. But if I drained the oil from the oil pan first, and removed the filter later, I don't get the oil mess in the catch basin.

Perhaps it is only a matter of time, that by draining the oil first I am giving the oil in the filter time to drain out? Perhaps it is relieving pressure in the engine? Not sure. But it works. Every time.

It's just a matter of developing a process that works, and being disciplined enough to follow it.

 

[PF52]

I think if you quickly remove the filter, you'll get a big mess of oil in the catch basin. As someone posted earlier - remove it slowly so it can drain back into the engine instead of into the catch basin. Or, better yet, loosen it partway and let it drain while you're draining the oil pan, rotating tires, etc. The analogy to cartridge filters is a good one. They stay full of oil until you "pop the cork" so to speak, by unscrewing the filter.