Oil Analysis - Slight Fuel Dilution - Leaky Injector(s)?

RIP TDI

Top Post Dawg
Joined
Feb 16, 2000
Location
Santa Barbara, CA
TDI
2015 GSW SE 6MT 2001 Golf GLS 5MT 1996 Passat Wagon
I've been doing Used Oil Analyses (Blackstone Labs) on my CRUA since new and have always had <0.5% fuel content (Blackstone says <2.0% is maximum normal). I'm now at 80,000 mi. and just got a 3.5% reading on my latest sample.

Has anyone else doing UOAs seen elevated fuel levels?

I'm assuming this is a leaking injector(s). The oil level hasn't risen, although I wouldn't expect it to with what seems to be pretty small dilution over a 10K mi./1 Year OCI. There haven't been any trouble codes thrown or starting/driveability anomalies to speak of.

Are there any injection values in VCDS that would be relevant to a leaking injector? Are there any other possible causes besides a leaking injector that I haven't considered?
 

ZippyNH

Veteran Member
Joined
Apr 22, 2015
Location
Southern NH
TDI
2015 JETTA TDI SE
Could have been kinda random...a extra few Regens due to change in driving style, trip length...or simply because the capacity isn't what it once was so Regens more often.
I might do an oil change earlier, test again, but I doubt the sky is falling.
 

prsa01

Veteran Member
Joined
Aug 16, 2000
Location
mpls,mn usa
TDI
14 jsw 6m, 96 B4v, miss my a4 :(
Also, any long crank starts? The one time I had water in the intercooler that required substantial cranking to start after draining had more fuel in the oil than usual (don't remember the exact number). Anything that requires substantial cranking can be getting fuel past the rings.
 

RIP TDI

Top Post Dawg
Joined
Feb 16, 2000
Location
Santa Barbara, CA
TDI
2015 GSW SE 6MT 2001 Golf GLS 5MT 1996 Passat Wagon
Also, any long crank starts? The one time I had water in the intercooler that required substantial cranking to start after draining had more fuel in the oil than usual (don't remember the exact number). Anything that requires substantial cranking can be getting fuel past the rings.
I thought about that but had only a couple of longer-than-normal cranking starts on this OCI and they were not that much longer; maybe a second or two. I doubt that would be enough to accumulate enough fuel in the oil to bump the dilution from 0.5% to 3.5%, but maybe it doesn't take much. Hopefully the next test sample will be a more definitive data point.
 

RIP TDI

Top Post Dawg
Joined
Feb 16, 2000
Location
Santa Barbara, CA
TDI
2015 GSW SE 6MT 2001 Golf GLS 5MT 1996 Passat Wagon
Are you using a fuel that has a higher bio content than you used to use?
I've used the same station for years and, by Calif. law, BD content is required to be somewhere between 5% and 20%. So, yes, bio content might have been higher than previous during the last OCI.
 

ZippyNH

Veteran Member
Joined
Apr 22, 2015
Location
Southern NH
TDI
2015 JETTA TDI SE
I've used the same station for years and, by Calif. law, BD content is required to be somewhere between 5% and 20%. So, yes, bio content might have been higher than previous during the last OCI.
Winner winner chicken dinner!!
Bet the bio content went up....
Results is more dilution...or cooler wx and a weak battery as it ages...course could be wear...
Still...I would change the oil at maybe 5k...or at least do a sample and have it tested. Then you can decide to investigate or simply adjust you oil change interval.
 

CleverUserName

Veteran Member
Joined
Oct 25, 2014
Location
NorCal
TDI
2014 OZ Cruze CTD & 2010 JSW 6MT & 2017 GMC Canyon CCLB ATX 2.8 Duramax
Blackstone doesn’t accurately measure fuel dilution. It could be significantly higher or lower than what they are telling you on the report.

Get a real oil analysis that uses GC to measure the actual FD and go from there.
 

ticaf

Veteran Member
Joined
Nov 15, 2018
Location
US Mid-Atlantic
TDI
Stock 2015 Golf SW S Manual TDI
80000miles in 9 years, I'd bet you are getting oil dilution from not driving enough.
What's your driving pattern? Has it changed in the past year.
 

RIP TDI

Top Post Dawg
Joined
Feb 16, 2000
Location
Santa Barbara, CA
TDI
2015 GSW SE 6MT 2001 Golf GLS 5MT 1996 Passat Wagon
80000miles in 9 years, I'd bet you are getting oil dilution from not driving enough.
What's your driving pattern? Has it changed in the past year.
Driving pattern and habits have remained exactly the same over the last 8 years and 7 UOAs.
 
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