UOA high fuel dilution, 2007 Honda Civic 1.8L

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Accidentally posted this to the general section before:

I had a UOA done today that returned 6.5% fuel content in the oil. This is after 11,500km (7200 miles) running Amsoil ASM 5w20 w/ an Amsoil filter. Used Castrol Edge w/ Wix filters previous to this oil change. The engine was hot when the sample was taken, a few minutes after parking.

Any ideas what might be causing this? The engine runs fine, used mainly for commuting to work 13km (8 miles) each way on the highway, but also longer road trips. I plan to install new plugs, as the current set have 120000km (75k miles), but I'm wondering if I might have a leaking injector. Anyone know how to test or diagnose this? UOA results below:

Aluminum: 9
Chromuim: 2
Copper: 1
Iron: 18
Lead: 0
Silicon: 15
Tin: 0
Silver: 0
Nickel: 0

Sodium: 12
Boron: 88
Calcium: 3079
Magnesium: 163
Zinc: 710
Phosphorus: 706

TAN: 0.14
TBN: 3.46
Fuel: 6.5%
Water: 0
Glycol: 0
Visc @40C: 47.3
 
8 mile trips are the culprit. 8 miles is barely getting the oil up to temp. PCV may need replacement as well.
I can say from experience in my vehicles that in 8 miles the oil isn't hot enough to prevent me cleaning the dipstick with my bare fingers.
Magnify that by 2 trips a day and you've got significant fuel dilution,as the used oil analysis shows.
Either shorten the interval and use a conventional to offset the cost,or take the car out for a weekly 30 mile run ensuring the oil gets up to operating temp and stays there the entire ride.
Hold 4000 rpm for 10 minutes after achieving operating temp. That should help evaporate the fuel in the oil.
 
Originally Posted By: Clevy
8 mile trips are the culprit. 8 miles is barely getting the oil up to temp. PCV may need replacement as well.
I can say from experience in my vehicles that in 8 miles the oil isn't hot enough to prevent me cleaning the dipstick with my bare fingers.
Magnify that by 2 trips a day and you've got significant fuel dilution,as the used oil analysis shows.
Either shorten the interval and use a conventional to offset the cost,or take the car out for a weekly 30 mile run ensuring the oil gets up to operating temp and stays there the entire ride.
Hold 4000 rpm for 10 minutes after achieving operating temp. That should help evaporate the fuel in the oil.


Well my trips are under 5 miles, and many are less than 1 mile..0.9 miles to work to be exact. No fuel dilution to report. Guess every engine is different? That number is pretty high for a non direct injected engine.
 
Originally Posted By: grantk

TAN: 0.14
TBN: 3.46
Fuel: 6.5%
Water: 0
Glycol: 0
Visc @40C: 47.3


Viscosity at 40 looks right; you'd think the fuel dilution would lower it. Amsoil 0w-20 ASM is supposed to be 47 new and Amsoil 5w-20 ALM is 50 new.
 
Originally Posted By: grantk
I made a typo up top, oil is in fact ALM 5w20.
OK, so you're only down 3 on viscosity at 40degC, should be 50 and you're at 47, not much diff. Yet... there's a lot of fuel dilution. Of course maybe a little oxidation and soot is thickening the oil to counter the fuel dilution(?). Thats Amsoil which shouldn't oxidize much though.
 
Tonight I'm going to change out the plugs, put in a new PCV, new oil and filter, and see what happens on the next UOA.

It doesn't look like too big a job to lift the fuel rail and injectors, so I may do that just to make there's no leaks. About a month ago I couldn't get it started one morning, like the engine was flooded. Let it sit for a few hours and then it fired up ok. No other problems though.
 
Originally Posted By: grantk
Tonight I'm going to change out the plugs, put in a new PCV, new oil and filter, and see what happens on the next UOA.

It doesn't look like too big a job to lift the fuel rail and injectors, so I may do that just to make there's no leaks. About a month ago I couldn't get it started one morning, like the engine was flooded. Let it sit for a few hours and then it fired up ok. No other problems though.


On a modern car like that, the engine control computer nails down the OBDII EPA-mandated air-fuel ratios, so if you're not getting a 'check engine' light with a corresponding code, I think it might be the old-fashioned way of getting fuel dilution: Piston rings worn a bit and letting in too much blow-by into the crankcase. (Seems odd since this is an excellent engine and you have used great oils/filters since new.) We hear about stuff like this with engines like I've got: a high-compression direct-injected engine, which yours is not.
 
I second the diagnosis of a leaky fuel injector. There was another R18 Civic with the same issue here a while back. His UOA should be still around. I can't remember the username, it might have been Artem. IIRC a bottle of injector cleaner solved his problem.
 
Originally Posted By: gpshumway
I second the diagnosis of a leaky fuel injector. There was another R18 Civic with the same issue here a while back. His UOA should be still around. I can't remember the username, it might have been Artem. IIRC a bottle of injector cleaner solved his problem.


Thanks gpshumway! I think I found the related post you mentioned, user was Patman. His problem seemed to have been fixed with injector cleaner, so I'll give that a try as well.
 
Originally Posted By: grantk
Thanks gpshumway! I think I found the related post you mentioned, user was Patman. His problem seemed to have been fixed with injector cleaner, so I'll give that a try as well.


Glad to help. Now that you found the post, yes it was Patman. Hopefully you're as lucky as he was, injector cleaner is a cheap fix.
 
I found a bottle of Redline SI-1 at a local parts place, so I got the PCV and plugs swapped, fuel system cleaner in, and new oil and filter. All of the old spark plugs looked normal, other than too much gap. The engine idles much nicer now with the new plugs
smile.gif


Now I just have to wait for the next UOA to see if it did anything! Will post the results when I do it.
 
Last edited:
Originally Posted By: gpshumway
I second the diagnosis of a leaky fuel injector. There was another R18 Civic with the same issue here a while back.


I had 7% fuel dilution and after running a bottle of Gumout Regane fuel system cleaner and a bottle of their fuel injector cleaner, it reduced my fuel dilution to nothing! I suspected a leaky injector because the car was hard to start when it had been sitting for long periods of time, but after running the cleaners through the fuel system, it began firing up instantly again with no problems!
 
Make sure your pcv is sealed properly .clean the rubber .clean the cv so it isnt oily then install.a bit of sand in your engine but not much ,probably due to not properly cleaned rubber of pcv .but so low that it isnt exactly a problem .as for your gas,might have one injector seal dying
 
What?!? Sand??

Originally Posted By: yvon_la
Make sure your pcv is sealed properly .clean the rubber .clean the cv so it isnt oily then install.a bit of sand in your engine but not much ,probably due to not properly cleaned rubber of pcv .but so low that it isnt exactly a problem .as for your gas,might have one injector seal dying
 
Originally Posted By: Patman
Originally Posted By: gpshumway
I second the diagnosis of a leaky fuel injector. There was another R18 Civic with the same issue here a while back.


I had 7% fuel dilution and after running a bottle of Gumout Regane fuel system cleaner and a bottle of their fuel injector cleaner, it reduced my fuel dilution to nothing! I suspected a leaky injector because the car was hard to start when it had been sitting for long periods of time, but after running the cleaners through the fuel system, it began firing up instantly again with no problems!


+1. I never sampled a UOA for my '10 Civic, but also experienced hard starting and stumbling for a period of time. I remembered Patman's ordeal so I ran a bottle of Amsoil PI through the system and it went away. I started running Techron every 10K and never had it again. Guessing it's not uncommon to R18 Civics.
 
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