Oil Smells Like Gas - Fuel Dilution?

[glock19]

I have a FB25 in my Legacy and with the oil consumption issues I've been monitoring the level closely. Lately, when I pull the dipstick it smells really strongly of gas. It's only been 2,000 miles since it was changed and I don't consider my usage severe. The car is used 95% of the time to do a 20 mile commute at 60mph. Is this a fuel dilution problem I should be concerned about? It's not scheduled for an oil change for another 5,000 miles so I'm not sure if it's worth changing just to get a UOA.

I took it to the dealer for them to look at multiple issues: the oil smelling of gas, a gas smell while using the heater, and a burning smell coming directly from the top of the block when I park it after commuting home. Of course they "didn't find anything" but I am looking for second opinions. Any ideas are appreciated.

 

[accent2012]

Is this car still on the factory fill oil?

Is this smell noticeable before or after you run the car for an extended period of time?

The fact that this is a boxer engine may contribute to the smell.

 

[dparm]

You don't need to change the oil to get a UOA. Blackstone sells a small hand pump and you just feed a small tube down the dipstick hole to pump a bit out. If you were closer to me, I'd loan it to you for free.

 

[glock19]

Originally Posted By: accent2012
Is this car still on the factory fill oil?

Is this smell noticeable before or after you run the car for an extended period of time?

The factory fill got switched out at 3,750 miles for Subaru Synthetic by the dealer and the car is now at 5,800 miles.

The burning smell from the block I definitely notice more after commuting home and the engine is hot. The gas smell in the oil I smell all the time regardless of temp.

 

[Quattro Pete]

Originally Posted By: glock19
It's not scheduled for an oil change for another 5,000 miles so I'm not sure if it's worth changing just to get a UOA.

Can you take a sample for UOA without changing the oil?

In my experience, even very little fuel in oil can make the oil stink of gas, so I wouldn't trust your nose on this. Do a UOA if you don't want to guess.

 

[glock19]

Originally Posted By: dparm
You don't need to change the oil to get a UOA. Blackstone sells a small hand pump and you just feed a small tube down the dipstick hole to pump a bit out. If you were closer to me, I'd loan it to you for free.


Thanks for the tip. I wish you were closer, $30 for that pump seems a little steep.

 

[accent2012]

Has it always smelled like fuel or has this happened recently?

After some googling, there seems to be an inherent problem with some of their boxer engines developing piston issues causing such a smell, but also a loss in oil.

 

[Quattro Pete]

I might add that not all labs actually test for fuel dilution. For example, Blackstone just estimates it based on flashpoint, which may not be very accurate.

 

[glock19]

Originally Posted By: accent2012
Has it always smelled like fuel or has this happened recently?

After some googling, there seems to be an inherent problem with some of their boxer engines developing piston issues causing such a smell, but also a loss in oil.


That's what I find interesting. The oil level has stayed steady with no consumption at all. There's a strong fuel smell but no oil consumption.

 

[glock19]

Originally Posted By: Quattro Pete
I might add that not all labs actually test for fuel dilution. For example, Blackstone just estimates it based on flashpoint, which may not be very accurate.


Do you know of a lab that will accurately test for fuel dilution?

 

[ARCOgraphite]

I've had over seven subarus in the past 25 years. A few thoughts:

How is the fuel mileage - if you are near 28-30mpg, I would think you're not loosing too much fuel past the rings.
AFA oil smell goes that would usually be on the EJ caused by a weeping filter gasket getting on the cats (which tightly surrounds the filter).
I didn't know they were putting the FB in the Legacy now - I thought they wrer still Ej - at least in 2012.

The ej is the better motor.

I don't like the idemitsu oil and Ive run 2 cases of it. Too light and I get mechanical knocking noises from the 2 engines ive run it in.
Make sure the sump is not overfilled. I would run it at least a 0.3L down from the full line - these engine burn oil in excess when topped off.

 

[accent2012]

for what its worth, my car's oil always has this fuel smell and it is increasingly common for newer cars to have a slight fuel smell.

My car's performance has not degraded over time and it's at 45k miles.

 

[Quattro Pete]

Originally Posted By: glock19
Do you know of a lab that will accurately test for fuel dilution?

I think Polaris does it right. I'm also trying to figure out how Wearcheck does it.

 

[glock19]

Originally Posted By: ARCOgraphite
I've had over seven subarus in the past 25 years. A few thoughts:

How is the fuel mileage - if you are near 28-30mpg, I would think you're not loosing too much fuel past the rings.
AFA oil smell goes that would usually be on the EJ caused by a weeping filter gasket getting on the cats (which tightly surrounds the filter).
I didn't know they were putting the FB in the Legacy now - I thought they wrer still Ej - at least in 2012.

The ej is the better motor.

I don't like the idemitsu oil and Ive run 2 cases of it. Too light and I get mechanical knocking noises from the 2 engines ive run it in.
Make sure the sump is not overfilled. I would run it at least a 0.3L down from the full line - these engine burn oil in excess when topped off.


Thanks for the tip. The dealer did the last oil change (the first one is free) and they actually overfilled on the dipstick by about half an inch. The level hasn't budged at all in 2,000 miles though. It also didn't burn any during the 3,750 on the factory fill.

I don't think I have a fuel leak though because I'm still averaging 29 mpg in mixed driving.

The 2013 Legacy is definitely using the FB25. It's actually stamped right on top of the block.

 

[glock19]

Originally Posted By: ARCOgraphite
The ej is the better motor.


Also, I'm curious why you said this.

Everything I've read is to the contrary. There are some piston ring issues but they supposedly solved the head gasket issues.

 

[mount]

Originally Posted By: ARCOgraphite
I didn't know they were putting the FB in the Legacy now - I thought they wrer still Ej - at least in 2012.


2012 was the last year of EJ in the Legacy.

 

[Trav]

Originally Posted By: ARCOgraphite
The ej is the better motor.


How so? I don't see anything that would make the EJ "better" on the contrary the FB looks like the more technically advanced engine.
The longer stroke, cam chain, 28 percent reduction in friction and variable valve timing on both intake and exhaust are a huge improvement.

Nothing bad with the EJ engines (i own one) but lets be honest it is long in the tooth and the timing belt replacement is a PITA. Time for it to be put out to pasture.
IMHO the FB looks like it will be a much friendlier engine as far as maintenance goes.

http://www.caranddriver.com/news/subaru-fb-series-engine-subaru-flat-four-engines

http://drive2.subaru.com/Win11/itsWhatMakes.htm

 

[ARCOgraphite]

Ive had issues with every engine that's used long timing chains - tensioner sticking etc. Our 11 Forester makes horrendous TC noises when warming up. There is already a tsb for tensioner issues. I do like the more square B/S relationship as Fuji was limited to increasing displacement by bore increase with the old engine. Our FB25 has VVT only on the intake cam.
In practice the old EJ engine with a VTEC variant was able to achieve better in town mileage with the 1 I valve operation vs the vvt on the FB. The wet Timing system is much harder on oil than the dry in the EJ. I don't like mini stationary valve lash adjusters as they are prone to varnishing. The EJ appears to have better high rpm power on the road.
I guess it comes down to personal design preference and the compromises made.