Fram XG3593A Cut Open - Lean-Burn 2015 Subaru WRX

[twX]

I cut open a FRAM Ultra XG3593A that was used for 7,000 km on a 2015 Subaru WRX. The car has been on a steady diet of Pennzoil Platinum since new. It's got an unconventional lean-burn engine tune, with AFR as high as 17.5:1 at cruising loads, and normally runs on 87 octane E10 instead of 91. I've put around 55,000 km on the engine with this tune. I'm not completely sure how the lean burn tune affects things like carbon buildup, soot production, etc, so I thought maybe the oil filter would provide some clues. I may do a UOA at the next oil change.

There was hardly any visible debris in the filter, aside from a large black chunk of something, about 5-6 mm long. It's very soft and feels like foam. It's not brittle at all goes back to its original shape after being folded over on itself. Any ideas as to what this is?

There were also a few tiny specs of metal that could be seen glittering in bright light, some are ferromagnetic. I did mangle the filter can when I cut it open, so some of it could be from that.

I installed a new PurolatorOne PL14615 with a proper 25 psi bypass setting, since the FRAM Ultra will bypass some oil on this engine, and I'd rather not have big black chunks of mystery material getting into my oiling system and clogging anything.

 

[JohnnyJohnson]

It will interest if you find any of those black chunks inside your Purolator on your Next OCI!

 

[Soft Cars]

That one isn't wire backed is it? Because if it was, I don't think you could move the pleat around like you did.

 

[twX]

That one isn't wire backed is it? Because if it was, I don't think you could move the pleat around like you did.

It is wire-backed. The pleats are difficult to spread. I expected to see the old style media when I opened it, since the box claimed that it was wire-backed. Edit: On a second look, it does appear to be the old style media.

 

[fantastic]

This filter looks to still be in excellent shape & hardly used. Not sure what the "foam" piece is.

 

[ZeeOSix]

It's got an unconventional lean-burn engine tune, with AFR as high as 17.5:1 at cruising loads, and normally runs on 87 octane E10 instead of 91. I've put around 55,000 km on the engine with this tune. I'm not completely sure how the lean burn tune affects things like carbon buildup, soot production, etc,

If it burns that lean most of the time, there would be minimum carbon and shoot left after combustion. I bet the spark plugs are relatively pretty clean for the mileage on them.

As far as the "foam" piece in the filter, hard to say if it was already in the filter or came from somewhere inside the engine.

 

[twX]

As far as the "foam" piece in the filter, hard to say if it was already in the filter or came from somewhere inside the engine.

I'm thinking it would be too large to get through the oil pickup screen, so it was probably already in the filter.

 

[JWC86]

What’s the purpose of a tune that lean? MPG?

Just curious.

 

[twX]

What’s the purpose of a tune that lean? MPG?

Just curious.

It improves fuel economy by reducing the amount of unburned fuel and by reducing pumping losses. It should help reduce fuel dilution as well. Fuel economy is improved by around 10% in highway cruising.

With some other tuning changes, and tires that less rolling resistance than stock, I tend to get around 6.6 L/100 km highway and 7.5-8.5 L/100 km in mostly city driving (outside of the cold winter months), which is as least as good as a non-turbo base Impreza typically gets.

The downsides of a lean burn tune are that it increases NOx production, and the catalytic converter doesn't work as well since there is no unburned fuel in the exhaust. Honda tuned some of their engines this way back in the 90's, but had to stop due to tightening emissions standards.

 

[ZeeOSix]

I'm thinking it would be too large to get through the oil pickup screen, so it was probably already in the filter.

Maybe ... maybe not. If it's soft and flexible it's possible it could have been forced through the pickup screen by the oil flow.

 

[twX]

One thing I forgot to mention is that the filter was changed after letting the car sit overnight, and there was almost no oil left in the filter. This is typical for these engines.

I thought that the smaller PurolatorOne might help reduce the time required for the engine to build pressure on a cold start and for the oil pressure light to shut off, since the FRAM is oversized and around 50% larger. It seems like it might be a bit better if anything, but the difference isn't very significant.

 

[malibuguy79]

That piece looks like it could be from some anti-rattle foam from maybe an engine cover or cowl plastic (i am unfamiliar with later WRXs) but i am sure you get what I am trying to explain.

 

[twX]

That piece looks like it could be from some anti-rattle foam from maybe an engine cover or cowl plastic (i am unfamiliar with later WRXs) but i am sure you get what I am trying to explain.

It's not anti-rattle foam, but your comment made me realize what it is.

The oil filter on this car is on top of the engine. The oil filter I used prior to the FRAM Ultra was oversized and I was concerned it might melt my hood insulation, so I put a couple of layers of high temperature insulating tape on top of the filter.

By the time I took the old filter off, the tape was a bit brittle. A chunk of it must have fallen onto the filter mounting plate near the filter gasket, and then fallen into the oil gallery when I took the filter off. Mystery solved!

 

[Merek]

Both of my Civic's have lean burn, 5 wire o2 sensor. It seems the Fram 3593a is being phased out in favor of the 9688, I read something where someone contacted Fram who basically said it's still being made but I know Walmart has removed them from their shelves in stores.

 

[Dave Hess]

Both of my Civic's have lean burn, 5 wire o2 sensor. It seems the Fram 3593a is being phased out in favor of the 9688, I read something where someone contacted Fram who basically said it's still being made but I know Walmart has removed them from their shelves in stores.

Civic HX ?

 

[Merek]

Civic HX ?

Yes, I have 97 & 99 models and both are 5 speeds along with 40+ mpg.

The Fram Ultra is rated for 20k miles or 32k km so I wonder why the OP changed it so soon? I would've changed the oil and used it again. Where did you find that piece in the filter, was it on the outside of the filter media? It's certainly not the adbv as Fram use an orange one in the Ultra filters.

 

[twX]

The Fram Ultra is rated for 20k miles or 32k km so I wonder why the OP changed it so soon? I would've changed the oil and used it again. Where did you find that piece in the filter, was it on the outside of the filter media? It's certainly not the adbv as Fram use an orange one in the Ultra filters.

I was going to use the Ultra for 2 OCIs, but I decided I didn't like the idea of using a filter with a low bypass setting, so I switched to the Purolator early. I'll probably change the PurolatorOne every OCI just so I can cut them open, even though the filters seem to stay pretty clean in this engine.

The foam piece was in the pleat with the largest spacing near the seam. See my last post for where I think it came from.