That upside-down oil filter

[Healey3000]

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.

[arizonaadam]

Anti drain back valve.

[Healey3000]

Originally Posted by arizonaadam

Anti drain back valve.

By that, do you mean there is one? In the engine or in the filter?

Thanks.

[fun2drive]

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...

[DrD]

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!

[Healey3000]

Originally Posted by DrD

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.

[BossMaverick]

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.

[jogosub]

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.

[plain OM]

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.

[mikelipke]

Originally Posted by jogosub

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.