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Discussion Starter #1
Hi,

The FB engine has a relocated oil filter, which is great for us DIY oil changers. On our 2002 OBW, I poke a hole in the bottom of the filter and let it all drain out by just cracking loose the threads.

However, a big advantage of the conventional mounting is that the filter is always full of oil, thereby assuring instant oil supply when cranking. Does the FB engine or filter have some kind of check valve to keep it from draining out when the engine is turned off?

BMW has used canister filters mounted this way for decades but they always have a check valve in the housing for this reason.

Thanks.
 

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Filter there is a write up that I saw maybe in the DIY here or on BITOG.com that actually cut them away and showed a couple different types of anti drain back valves. I can tell you I just changed an friends Forester with the exact same engine and filer and it was full of oil and had to let it drain as best I could and wipe the excess off the surrounding filter housing...
 

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Depending on the quality of the anti-drainback valce, about the only time the filter won't be full of oil is when you first install it - that's about the only drawback of the inverted filter arrangement (though a pretty minor one) - you can't pre-fill the filter with oil when installing a new one.

Also - I haven't changed a filter in an FA/FB series engine, but the comment above makes me wonder how well the little drain tray around the filter works... you could really make a mess if it overflows when removing the filter!
 

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Discussion Starter #6
Depending on the quality of the anti-drainback valce, about the only time the filter won't be full of oil is when you first install it - that's about the only drawback of the inverted filter arrangement (though a pretty minor one) - you can't pre-fill the filter with oil when installing a new one.

Also - I haven't changed a filter in an FA/FB series engine, but the comment above makes me wonder how well the little drain tray around the filter works... you could really make a mess if it overflows when removing the filter!
True, a perfect check valve means that the ony time you put the engine at risk is at first start after a new filter goes on. However, check valves can leak and sometimes fail.

I had a BMW E34 and one day I noticed that the oil pressure light was taking longer than normal to go out. Some sleuthing around led me to the conclusion that the check valve in the floor of the canister housing had failed. I had to purchase an entire housing and did so. A month later, the same thing happened. Fortunately, there was a warranty on the part so it didn't cost me anything. The dealership I bought the part from would not believe my diagnosis so I left the car with them and explained my diagnostic procedure. They finally agreed I was right and installed the unit for me!

Let's hope the Subaru filters have decent valves.
 

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I hate to be the bringer of bad news but the oil in the filter does drain down. The anti-drain back valve prevents the dirty oil from draining back but the oil will still slowly drain down the center tube.

I've done two oil changes on my car so far. For the first oil change, I let the car sit for about 30 minutes before removing the filter. The filter was empty. For the second oil change, I let the car sit for about 10 minutes before removing the filter. The filter wasn't as empty as the first time but it wasn't full either.

I have no idea how the dry oil starts will fair for long term durability. I do know that the oil light goes off extremely fast so I'm guessing the car has a very high flow oil pump. I'm hoping Subaru did their homework and enough testing to make the oil filter positioning won't cause any premature engine wear.
 

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Anti Drainback Valve

I am looking at OEM filter P/N 15208AA160 (that dealer claims is for 2013 OB). Inside (deep in the filter) I see some kind of "valve" that I did not see in previous OEM filters.

I am also looking at the aftermarket Purolator L14614 - that also should be applicable for this model - per Purolator cross reference manual.
The cross section of the Purolator filter is showing (and description claims) that anti-drain valve minimizes dry engine starts although it's not clear, if that applies to the inverted oil filters...

I am sure Subaru R&D thoroughly considered this issue when designing the 2013 OB engine this way.
 

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On the Subaru filter, the Anti-drainback valve is the rubber piece that can be seen through the outer circle of smaller holes in the base of the filter. This is where the oil comes in from the pump, and once behind the rubber seal, presumably shouldn't drain back out.

The large center opening that also is the threaded section is the outlet of the filter and this goes to the engine oil passages.

The filter's pressure sensitive by-pass valve is at the other end of the center tube, and what can be seen when looking straight down into the tube.

Different manufacturers use different designs for their ADB valves and for by-pass valves, but their overall effectiveness is usually the same. However, the Subaru filter is designed with a by-pass valve spec of 23 psi, whereas most other aftermarket oil filters that are listed by their mfrs for Subaru have valves with lower specs.
 

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I am sure Subaru R&D thoroughly considered this issue when designing the 2013 OB engine this way.
So do the chemical engineers that design and certify the modern oils to have certain "film strength" and "shear strength" capabilities.
My Toyota Tacoma V6 has a filter mounted the same way (only difference is that they have a nipple on the bottom of the filter platform to drain away any oil that leaks out of the filter into a pop bottle or plastic tube). That engine has been produced since 2005, and is well regarded as at least a 250,000 mile engine. Since 2005, that engine has powered millions of trucks to billions of miles, with a great reputation. An empty oil filter every start up has not seemed to hurt its reliability at all.
Relax, and enjoy your vehicle. Modern oils look smell and taste the same, but they are very different from lubricants from the 50's, and vehicle manufacturers are actually designing engines and transmissions around these oils' cababilities. Oh, and they are more reliable than ever. Longer lasting, too.
 

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On the Subaru filter, the Anti-drainback valve is the rubber piece that can be seen through the outer circle of smaller holes in the base of the filter. This is where the oil comes in from the pump, and once behind the rubber seal, presumably shouldn't drain back out.

The large center opening that also is the threaded section is the outlet of the filter and this goes to the engine oil passages.

The filter's pressure sensitive by-pass valve is at the other end of the center tube, and what can be seen when looking straight down into the tube.

Different manufacturers use different designs for their ADB valves and for by-pass valves, but their overall effectiveness is usually the same. However, the Subaru filter is designed with a by-pass valve spec of 23 psi, whereas most other aftermarket oil filters that are listed by their mfrs for Subaru have valves with lower specs.
The anti-drain back valve prevents the oil from escaping the filter through one of two possible routes. Unfortunately, there is nothing stopping the oil from escaping from the other route (through the filter media and out the center exit hole of the filter). With the engine off and the filter mounted above the engine, there is nothing preventing the oil from draining out of the exit of the filter and out of the oil passages of the engine. Granted, this isn't an instant drainage but it still happens.

Bypass valves have nothing to do with preventing the oil from draining out of the filter when the engine is off.
 

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So do the chemical engineers that design and certify the modern oils to have certain "film strength" and "shear strength" capabilities.
My Toyota Tacoma V6 has a filter mounted the same way (only difference is that they have a nipple on the bottom of the filter platform to drain away any oil that leaks out of the filter into a pop bottle or plastic tube). That engine has been produced since 2005, and is well regarded as at least a 250,000 mile engine. Since 2005, that engine has powered millions of trucks to billions of miles, with a great reputation. An empty oil filter every start up has not seemed to hurt its reliability at all.
Relax, and enjoy your vehicle. Modern oils look smell and taste the same, but they are very different from lubricants from the 50's, and vehicle manufacturers are actually designing engines and transmissions around these oils' cababilities. Oh, and they are more reliable than ever. Longer lasting, too.
That's what I thought Mike - thanks for formulating this better than me!
 

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IMHO, concern about this filter position falls into the "drive more, worry less" category. If I wanted to worry about something, it would be a cold engine (any engine) getting lubrication on startup. A read of the background material on motor oil on BITOG (Bob Is The Oil Guy) clearly states this as the continuing issue with oil over the years, and it remains so today. Over the life of the engine, far more wear occurs in the first minute or so after the engine starts than when it's warmed up and running. This is due to a number of technical factors, but it's where the modern oils really shine compared to their counterparts of days gone by. The so-called "multi-weight" oil is really an oil that pumps like a lower weight oil, e.g., a 5W-30 oil is 30 weight, but pumps like 5 weight. A 0W-40 is a 40 weight that pumps like a 0 weight. But warmed up and running is where the engine and oil are designed to be- and it'll never be that way at a cold start.
 

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I am looking at OEM filter P/N 15208AA160 (that dealer claims is for 2013 OB). Inside (deep in the filter) I see some kind of "valve" that I did not see in previous OEM filters.

I am also looking at the aftermarket Purolator L14614 - that also should be applicable for this model - per Purolator cross reference manual.
The cross section of the Purolator filter is showing (and description claims) that anti-drain valve minimizes dry engine starts although it's not clear, if that applies to the inverted oil filters...

I am sure Subaru R&D thoroughly considered this issue when designing the 2013 OB engine this way.
What kind of prices are you seeing for the after market filters? Stopped by my dealer yesterday and picked up filters for my OB. $5.50 each. That includes the crush washer for the oil pan plug. No washer for the filter.

I don't think $5.50 for a filter is unreasonable.
 

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What kind of prices are you seeing for the after market filters? Stopped by my dealer yesterday and picked up filters for my OB. $5.50 each. That includes the crush washer for the oil pan plug. No washer for the filter.

I don't think $5.50 for a filter is unreasonable.
$ 5.50 is quite reasonable. Not all folks out there are close to the dealer, where they can buy OEM filters. Some have PepBoys, TrackAuto or NAPA store in the neighborhood and five or so dollars is quite reasonable for OEM or generic.
 

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. . . With the engine off and the filter mounted above the engine, there is nothing preventing the oil from draining out of the exit of the filter and out of the oil passages of the engine. Granted, this isn't an instant drainage but it still happens. . . ..
I tend to wonder if that would happen in any normal engine off time frame, if ever.

In order for the oil in the filter to drain down the outlet side into the engine oil passages, and through these, through the bearings, cams, solenoids etc, back to the pan, the oil that was in the filter would have to be replaced by something which I presume you are saying is air.

The oil passages in the block are higher than the oil pan pump pickup, which is submerged. So air cannot come into the filter from the pump (filter inlet) side unless there's air leaks in the oil pump pickup system, which otherwise is sealed.

The outlet side of the filter goes down to the block oil passages and from there to journals, bearings, cams and solenoids. Oil can drain from these back to the pan (that's the normal flow), but it seems to me it would take a very long time, if ever, for air to work it's way back up these same paths to replace the oil in the filter and in the oil passages.

I note also that the oil passages are higher than the oil pump pickup in the sump. The siphon effect is toward the pan, not through the engine oil passages and this is prevented by the anti-drainback valve.

I wouldn't be concerned unless the car were being stored for a very long time, in which case the same dry upper block passages might be expected with any engine.

My reference to the by-pass valve was in regard to the Purolator filter that was mentioned in the previous post. My objective was to demonstrate that whether or not a filter has an anti-drainback valve isn't the only issue to be considered when deciding to use a different make.
 

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Methinks this is being over thought. Just drive the car. Enjoy the car. If something happens before a quarter million miles, we can then blame Subaru for doing something stupid with the filter. Until then, I'm gonna enjoy the engineering that put the filter in such a great spot.
 

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Methinks this is being over thought. Just drive the car. Enjoy the car. If something happens before a quarter million miles, we can then blame Subaru for doing something stupid with the filter. Until then, I'm gonna enjoy the engineering that put the filter in such a great spot.
I second that!
 

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Someone I know who has one says a little comes out into the little cup, and sits in a small groove/trench in the 'cup', and you need to use a rag to soak it up.
 
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