Fuel Dilution

[uraniumrich]

Just curious but what problem will changing the oil earlier solve?

Ptahkeem hit it on the head. The amount of dilution will increase over time which reduces the effectiveness of the oil. That's why Blackstone suggested I should check the dipstick to keep an eye on the oil level. If it's increasing, then that's fuel being added to the oil.

 

[EOD Guy]

IMO, 5K is a good interval to keep the hydrocarbon breakdown that gets deposited into the oil, to a manageable level. For me It's a balance of money vs actual positive gain........ 5K oil still has some transparency to it when drained. So in my way of thinking it would still be able to absorb/encapsulate more crud. It puts my mind at ease for the small amount of money I spend every 5K for fresh oil/filter.

Others might get the same assurances at 1K oil changes, but to me that's not worth the money. Some will advocate for the 10K oil changes as that's what the owners manual states...... yadda, yadda

 

[kmershly]

IMO, 5K is a good interval to keep the hydrocarbon breakdown that gets deposited into the oil, to a manageable level. For me It's a balance of money vs actual positive gain........ 5K oil still has some transparency to it when drained. So in my way of thinking it would still be able to absorb/encapsulate more crud. It puts my mind at ease for the small amount of money I spend every 5K for fresh oil/filter.

Others might get the same assurances at 1K oil changes, but to me that's not worth the money. Some will advocate for the 10K oil changes as that's what the owners manual states...... yadda, yadda

On all my cars, I do one break-in oil change at 1,200 miles and then every 5k.

I recently tore down my E92 M3 S65 engine and it was clean as a whistle, no varnish, looked almost brand new, it was so clean.

Because it was so clean, I ended up doing very little to the engine other than changing out the main and rod bearing, as well as changing out a number of bolts from OEM to ARP.

I credit the engine being as clean and healthy as it was to doing oil changes with high quality oil every 5k.

 

[uraniumrich]

On all my cars, I do one break-in oil change at 1,200 miles and then every 5k.

I recently tore down my E92 M3 S65 engine and it was clean as a whistle, no varnish, looked almost brand new, it was so clean.

Because it was so clean, I ended up doing very little to the engine other than changing out the main and rod bearing, as well as changing out a number of bolts from OEM to ARP.

I credit the engine being as clean and healthy as it was to doing oil changes with high quality oil every 5k.

Gotta love an engine that needs the bearings replaced as part of regular maintenance. Love the E92 - maybe the best generation of the M3. Any issues with VANOS? Oil leaks?

 

[uraniumrich]

IMO, 5K is a good interval to keep the hydrocarbon breakdown that gets deposited into the oil, to a manageable level. For me It's a balance of money vs actual positive gain........ 5K oil still has some transparency to it when drained. So in my way of thinking it would still be able to absorb/encapsulate more crud. It puts my mind at ease for the small amount of money I spend every 5K for fresh oil/filter.

Others might get the same assurances at 1K oil changes, but to me that's not worth the money. Some will advocate for the 10K oil changes as that's what the owners manual states...... yadda, yadda

The oil analysis reports tell us whether the oil is still good at 5K. With the exception of the fuel dilution, my oil reports have looked really good. The same holds true for all of the oil analysis on my other cars - the oil still has life at 5K miles. I think you hit it on the head - you can change your oil more often, but the economics don't make sense. The 10K mile people haven't seen what an engine looks like after regular maintenance on that interval. I've watched Eric tear down well over 100 engines on his channel, and 10K mile oil changes have killed more than their share of engines. It ain't pretty!

 

[RUN-8]

On all my cars, I do one break-in oil change at 1,200 miles and then every 5k.

I recently tore down my E92 M3 S65 engine and it was clean as a whistle, no varnish, looked almost brand new, it was so clean.

Because it was so clean, I ended up doing very little to the engine other than changing out the main and rod bearing, as well as changing out a number of bolts from OEM to ARP.

I credit the engine being as clean and healthy as it was to doing oil changes with high quality oil every 5k.

BMW probably could have helped their reputation over the last 20 years by recommending 5K oil change intervals instead their asinine 15K/1 year OCI.

How did your rod and main bearings look? What is your mileage?

I have to wonder if a more aggressive OCI interval of 3K-5K might have saved a lot of the E60/E61 M5 and M6 V10’s from eating rod and main bearings.

 

[kmershly]

Gotta love an engine that needs the bearings replaced as part of regular maintenance. Love the E92 - maybe the best generation of the M3. Any issues with VANOS? Oil leaks?

The bearings were actually not that bad, they showed wear, probably more wear than they should have, but I wanted to replace the OEM bearings with BE bearings which are far superior

VANOS, I checked the solenoids to make sure they were clean and they went right back in. Oil Leaks, it is a BMW, if it didn't at least have one leak, I would have thought that I had accidentally purchased a Toyota.

I fixed the one leak from the oil filter housing gasket and that was that.

All kidding aside, if you take care of any car, but in my case, BMWs, they will last longer and have less issues than if you don't.

BMW probably could have helped their reputation over the last 20 years by recommending 5K oil change intervals instead their asinine 15K/1 year OCI.

How did your rod and main bearings look? What is your mileage?

I have to wonder if a more aggressive OCI interval of 3K-5K might have saved a lot of the E60/E61 M5 and M6 V10’s from eating rod and main bearings.

All bearings showed some wear, not terrible, I have seen worse, I recently bought an F80 M3 with a spun bearing on cylinder 6 and I am sure it was because of lack of maintenance.

All the bearings on that M3 were in really bad condition, so yeah a more aggressive oil change interval would help with that.

However, I wanted to swap out the bearings from the OEM to BE bearings because they are known to be better.

On my E92 M3, I have 60,000 miles on the clock.

 

[ultane]

The oil analysis reports tell us whether the oil is still good at 5K. With the exception of the fuel dilution, my oil reports have looked really good. The same holds true for all of the oil analysis on my other cars - the oil still has life at 5K miles. I think you hit it on the head - you can change your oil more often, but the economics don't make sense. The 10K mile people haven't seen what an engine looks like after regular maintenance on that interval. I've watched Eric tear down well over 100 engines on his channel, and 10K mile oil changes have killed more than their share of engines. It ain't pretty!

DUDE….. Now you have me stuck on watching his videos on doing an LS swap in an 80 series Land Cruiser (LX460)… something that I have thought about doing, if I live long enough, and Miss Daisy’s engine goes tits up.

 

[jpto]

I had a Prius that was unhappy when it was shut off when the ICE was running and it was colder out. It would run rough on the next startup until it came up to temp.

My theory was that the car was trying to bring the ICE back up to operating temp and running richer than usual leaving unburnt gas in the engine during shutoff.

I know LC is a different type of hybrid but maybe I’ll try waiting to shut off the car like the Prius.

 

[kmershly]

DUDE….. Now you have me stuck on watching his videos on doing an LS swap in an 80 series Land Cruiser (LX460)… something that I have thought about doing, if I live long enough, and Miss Daisy’s engine goes tits up.

That does sound like a fun project.

I have not personally done a LS swap yet, I know someone who has done two LS swaps, but neither was on a Land Cruiser.

 

[uraniumrich]

DUDE….. Now you have me stuck on watching his videos on doing an LS swap in an 80 series Land Cruiser (LX460)… something that I have thought about doing, if I live long enough, and Miss Daisy’s engine goes tits up.

Eric is awesome. His facility is in my neck of the woods. His LC shows up from time to time in videos. The more you watch him tear down engines, the more you realize how important it is to do regular oil changes and to use the right gas. Just because the LC can run on non-premium fuel, doesn't mean we should.

 

[bluebullet]

Is it possible that air was so cold that the engine oil never got hot enough for the fuel to fully evaporate and go out the crankcase? To my idiot level of understanding some amount of blow-by is pretty much inevitable which is why running a warm engine for a certain amount of time is needed for that sneaky fuel to vaporize and be removed through the crankcase ventilation system. Same reason taking lots of short trips leads to a gassy smelling dipstick (insert wisecrack here).

Is there a name for people who go around sniffing dipsticks? Wisecrack submitted...

 

[42UMOG]

I'm wondering if anyone else has noticed a significant amount of fuel dilution in their oil analysis? This is my third oil change (with analysis with each change). While the change interval was a little longer than I'd like (5,543 miles), I was surprised to see what seems like a significant amount of fuel in the oil. As a result, the flashpoint of my oil was down significantly. Beyond stating the obvious - fuel is the enemy of our oil - can anyone shed some light on potential causes?

Just a little background on this oil change. The change was completed after a 6 hour road trip in very cold weather. We finished the road trip on a Monday night, the engine sat overnight, and then I changed the oil the next day (in other words, the engine was cold.) The temperature in my garage was kept in the 40-50 degree range. I had to choose between changing the oil a little early (about 4,500 miles) or a little late (5,500 miles). Given that I'm using high quality oil (Amsoil Signature Series), I wasn't overly concerned about the extended change interval.

Any thoughts on this?
View attachment 29247

I have not done an analysis, but I can tell you when I change the oil, I am not striking a match close by. Never had a vehicle that reeks this bad when I change the oil. However, this is my first hybrid. Maybe that's normal. I have 9K on it now and all 3 oil changes I have done have smelt the same.

 

[Doggman1525]

Not to drag this into the Spanish Inquisition that is the myriad of "why aren't I getting the published MPG" threads but there are reasons why a small displacement turbo might run rich under certain conditions when pulling around a three ton vehicle and therefor leaving some un-combusted fuel behind that works its way into crankcase. Doesn't require a PhD in multidimensional physics to comprehend, just plain ole' thermodynamics and an understanding of how the CAFE testing works, which I presume Toyota understands far better than I.

https://youtu.be/9aO2vC_iMTI?si=ouX2LMoCc-6gZ0uy

Until proven otherwise I'll trust that enough thought went into the design that this engine isn't going to just implode at 60k - though 5k oil changes over 10k and premium fuel (there, I said it) certainly seems like cheap insurance against early failure.

 

[uraniumrich]

I have not done an analysis, but I can tell you when I change the oil, I am not striking a match close by. Never had a vehicle that reeks this bad when I change the oil. However, this is my first hybrid. Maybe that's normal. I have 9K on it now and all 3 oil changes I have done have smelt the same.

This is not my first Toyota hybrid. But, this is much different than the standard hybrid they put in cars like the Camry, Rav4, and Venza. Those hybrids focus on MPG (I was gettin 42+ mpg with the Venza during the warmer months). I never noticed any issues with my regular hybrid, but I also didn't do any oil analysis on the Venza (I sold at 40K, so...not concerned.)

 

[AuraLC250]

I'm wondering if anyone else has noticed a significant amount of fuel dilution in their oil analysis? This is my third oil change (with analysis with each change). While the change interval was a little longer than I'd like (5,543 miles), I was surprised to see what seems like a significant amount of fuel in the oil. As a result, the flashpoint of my oil was down significantly. Beyond stating the obvious - fuel is the enemy of our oil - can anyone shed some light on potential causes?

Just a little background on this oil change. The change was completed after a 6 hour road trip in very cold weather. We finished the road trip on a Monday night, the engine sat overnight, and then I changed the oil the next day (in other words, the engine was cold.) The temperature in my garage was kept in the 40-50 degree range. I had to choose between changing the oil a little early (about 4,500 miles) or a little late (5,500 miles). Given that I'm using high quality oil (Amsoil Signature Series), I wasn't overly concerned about the extended change interval.

Any thoughts on this?
View attachment 29247

Here is a summary of your oil analysis report from Blackstone Laboratories:

Overall Condition:​

• The wear metals have come down to normal levels, indicating that the engine is breaking in well.
• No coolant contamination detected (low levels of potassium and sodium).
• Air filter is working properly (low silicon levels).
• Insolubles remain low, showing the oil filter is functioning correctly.

Potential Concern:​

• Fuel dilution: The flashpoint is low (295°F), indicating 4.5% fuel dilution. This suggests excess fuel in the oil, which could be due to a fuel system issue. Keep an eye on oil levels and dipstick appearance.

Key Metal Wear Readings (PPM):​

• Iron (13): Within normal limits, indicating typical wear.
• Aluminum (7): Normal, no excessive wear.
• Copper (5): Well within limits.
• Lead (0): No concerning bearing wear.
• Molybdenum (193): Additive from oil, normal level.
• Silicon (22): No contamination from dirt.
• Calcium (1024), Magnesium (781), Zinc (642): Healthy additive package.

Oil Properties:​

• Viscosity (6.62 cSt @ 100°C): Slightly lower than the expected range, likely due to fuel dilution.
• Flashpoint (295°F): Low, indicating fuel contamination.
• Water & Coolant: 0.0% (no contamination).
• Insolubles (0.2%): Low, confirming clean operation.

Conclusion & Recommendation:​

• The engine is in good shape, and wear levels are normal.
• Fuel dilution is the only concern (4.5%)—this may indicate a fuel system issue (leaking injector, excessive idling, or rich fuel mixture).
• Keep an eye on oil levels and check for fuel odor on the dipstick.
• If fuel dilution increases in future tests, further investigation may be needed.

 

[Bad1975]

No Fuel dilution in my report, albeit only 1,760 miles on the oil.

 

[ptahkeem]

No Fuel dilution in my report, albeit only 1,760 miles on the oil.
View attachment 30437

Out of curiosity, what are you driving habits? Do you do more long distance driving, mixed or short distance driving?

 

[Bad1975]

Mixed driving, but it never sees not getting up to operating temperature. All trips are at least 10 miles at 40 MPH just to get into town with the first mile being 25-30 MPH.

 

[jmqb1]

Just wanted to chime in i just changed my oil for the 4th time at 15k miles and there is a heavy fuel smell. Even the dipstick smells like gas. Haven't got it analyzed.