Castrol Euro 5W40 | 3755 mi | 2018 Honda CRV 1.5l - High Fuel

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Excessive fuel dilution continues on our 2018 CRV. This time, though, the wear metals are nearly normal for this engine. Last year I adopted a new strategy to contain the worst of the fuel dilution in a short, winter OCI. This means I'm changing the oil right before the cold winter hits, and changing again when the winter freezes stop and warm weather becomes consistent. The previous OCI was from 11/19 to 3/17, and this OCI was from 3/17 to 11/10. Despite both UOAs showing >5% fuel, this OCI had a nearly normal wear metal profile. I'm guessing this OCI was closer to 6% while the previous OCI was closer to 10% (both are >5%).

Universal Averages for this engine (according to Blackstone) show a total of 5.0 ppm metals per 1000 mi.
This most recent OCI got 5.9 ppm per 1k.
The previous winter OCI got 15.3 ppm per 1k 😲

This car's best result was 2.6 ppm per 1k during a 4300 mi OCI that included a 2700 mi road trip.

This engine appears to wear very well as long as the highway miles are dominant, but becomes horrible when short trips are dominant, due to the high fuel dilution.

A little about this OCI's drive pattern: it was still a low mileage OCI with an average of 15.8 miles per day (3755 mi in 7.5 months), but sprinkled in with the short trips were several 100 mi round trips and one 600 mi round trip in the middle of July. Iron is less than half from the previous OCI (3.5ppm per 1k vs 8.9ppm per 1k).

Using an API SP, high TBN Euro 5W40, the TBN did still drop a lot, but still had plenty of life left. Oxidation only rose 5 pts but Nitration rose 9 pts.

Viscosity dropped by 24% but part of that may be the lower viscosity carryover from the previous oil. I put the same oil in, so we'll see next Spring what the viscosity looks like.

The top, light blue line marked 'BL' is the virgin analysis of Castrol Edge Euro 5W40. Iron starts at 3 and Silicon starts at 6. I guess that means I can subtract those amounts from my UOA? If so, that would drop Iron from 13 to 10 and Silicon from 16 to 10. The air filter has <7k miles on it. The oil filter was a Fram Ultra which had been on for 2x OCI. It was removed and replaced with a Fram Endurance 7317.

18 CRV 111024.webp
 
Excellent write up! I would agree to subtract ppm from the VOA. Very interesting notes about the differences. I'd say possibly the biggest contribution is short / winter trips / more fuel like you mention. Looks like your best run so far within these three samples disregarding any previous samples. Hard to compare w/the 2700 mile trip since that may not be "Normal" for every ODI. Good notes to have nonetheless & this 5.9 ppm isn't too far off for not having a long highway trip like that. Keep it up! I think it's very neat to see what you can learn from these.\
 
I was looking at how much more Nitration climbed than Oxidation and saw this on OAI fact sheet:
Nitration indicates excessive "blow-by" from cylinder walls and/or compression rings. It also indicates the presence of nitric acid, which speeds up oxidation. Too much disparity between oxidation and nitration can point to air to fuel ratio problems. As oxidation / nitration increases, so will total acid number and viscosity, while total base number will begin to decrease. Nitration is primarily a problem in natural gas engines.
Seems to be another indicator of fuel dilution. Anyone else know much about nitration?
 
I was looking at how much more Nitration climbed than Oxidation and saw this on OAI fact sheet:

Seems to be another indicator of fuel dilution. Anyone else know much about nitration?
Seems about right. Fuel has various additives with N compounds - if they partially breakdown in combustion and slough off into the oil - adds to nitration and oxidation of the oil itself.
 
Hard to compare w/the 2700 mile trip since that may not be "Normal" for every ODI.
Here is that UOA, btw. My memory was a couple hundred miles off :) :
 
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