Fuel Dilution

[Blue Bear]

My entire life I thought gas in the oil was caused by unburnt miniscule particles of getting trapped by the top ring and blowing by the 2nd ring and the oil ring on the next compression stroke. Blow by in most cases is due to ring gap and/or cylinder wall condition.

That's one of my concerns. Is the fuel dilution due to having low spring tension to increase the fuel mileage? If I continue to see the same dilution, then I'll probably start changing my oil more frequently than every 5K.

 

[Blue Bear]

Very informative and interesting. So I should not idle so long on these cold winter starts as I have been doing before I pull out of driveway.

Here's a great video on cold idling and the time it takes to warm up the powertrain -

 

[Blue Bear]

The fuel dilution went from 1.56 at 1200 mile oil change, to 2.56 at the 4500 mile oil change. I changed the oil and filter at 4500 miles since we were going out of town and wouldn’t be back until the odometer was at ~6,000 miles.

I do not know what the ‘units’ are for ‘fuel dilution’.

If I had to guess, the units are percent, not ppm. Measuring fuel dilution in ppm would mean that the fuel dilution is insignificant. 1 ppm = 0.0001 %. The dilution on my sample was 4.5%.

 

[TakaraLC]

Do you usually drive short distances in winter? Engine will run rich before temp is reached and unburned fuel can blow by into the oil. Cold weather can exacerbate this issue since it will run rich over a longer period.

 

[ptahkeem]

Ooc have any of you guys monitored your engine misfire counts? I’ve done a few oil changes on my vehicle and have noticed a slight fuel smell. Wondering if it might be caused by random misfires? I say this because obd2mx reader will report 1 or 2 misfires every so often. I always thought this might be device error as obd2mx themselves say that the readings are likely device error but it’s something to wonder about…

 

[Blue Bear]

Do you usually drive short distances in winter? Engine will run rich before temp is reached and unburned fuel can blow by into the oil. Cold weather can exacerbate this issue since it will run rich over a longer period.

My daily drive is about 20 minutes each way and includes an extended stretch of 55 mph. I don't think this is the issue, but it's something I've considered. Keep in mind that the last oil change included two trips of six hours at highway speeds - 75 mph - just before the oil change, too.

 

[TakaraLC]

Yeah misfire and knock sensor data may indicate an issue with incomplete combustion.

 

[Blue Bear]

Yeah misfire and knock sensor data may indicate an issue with incomplete combustion.

Which brings up everybody's favorite topic...Fuel Grade. Yes, my LC gets 91 or 93 octane 100% of the time.

 

[Mookie242]

This often happens in delivery trucks. Your problem is probably excessive wear due to long periods of idling, frequent short trips, and living in a cold climate.

 

[jbe2289]

My daily drive is about 20 minutes each way and includes an extended stretch of 55 mph. I don't think this is the issue, but it's something I've considered. Keep in mind that the last oil change included two trips of six hours at highway speeds - 75 mph - just before the oil change, too.

Do you watch your temp gauge? I drive about 20 minutes each way to work too about 10 miles with about 6 of that highway posted at 55 MPH, but the traffic is moving at 65-70 MPH, usually, including myself. When the temp is below 40, then engine and trans don’t reach full operating temp, yet alone sit at it long enough to boil off water and gas. I tend to drive extra 5+ miles over the winter on my way home to at least get the oil and transmission fluid to normal operating temperatures for a few minutes to hopefully boil off any water.

 

[Blue Bear]

Do you watch your temp gauge? I drive about 20 minutes each way to work too about 10 miles with about 6 of that highway posted at 55 MPH, but the traffic is moving at 65-70 MPH, usually, including myself. When the temp is below 40, then engine and trans don’t reach full operating temp, yet alone sit at it long enough to boil off water and gas. I tend to drive extra 5+ miles over the winter on my way home to at least get the oil and transmission fluid to normal operating temperatures for a few minutes to hopefully boil off any water.

Yes, I watch my temp. I keep my LC garaged and I have a well insulated home and garage. So, the LC doesn't get real cold. The temperature gauge on the LC is imprecise, at best, but does appear to show that my engine/transmission/coolant is fully up to operating temperature by the time I arrive at work.

 

[ptahkeem]

Yes, I watch my temp. I keep my LC garaged and I have a well insulated home and garage. So, the LC doesn't get real cold. The temperature gauge on the LC is imprecise, at best, but does appear to show that my engine/transmission/coolant is fully up to operating temperature by the time I arrive at work.

I too have noticed imprecise temp measurements or at least “slow” readings that tend to spike for engine coolant specifically. My obd2mx oddly won’t read transmission temps with the newer Toyotas but my old cheap veepeak can. However, the veepeak doesn’t seem to be able to read misfire information. I do wonder how accurate the obd2mx data is though… This is the second car that it thinks is having 1-2 misfires every other drive.

 

[ultane]

Here's a great video on cold idling and the time it takes to warm up the powertrain -

This is a great video!

 

[ultane]

The fuel dilution went from 1.56 at 1200 mile oil change, to 2.56 at the 4500 mile oil change. I changed the oil and filter at 4500 miles since we were going out of town and wouldn’t be back until the odometer was at ~6,000 miles.

I do not know what the ‘units’ are for ‘fuel dilution’.

As a follow up..

Lake Speed Jr. and I exchanged a few emails concerning the rising fuel dilution value. He strongly recommended that I watch the video below. Lake Speed Jr.’s other gig involves piston rings. It makes since now, since I was a little shy on the initial break-in drives in Miss Daisy. I guess I need to get out and ‘let ‘er rip’ some, since I wasn’t near as aggressive as they are in the video. I hope this ends Miss Daisy’s fuel dilution issue, but I fear it won’t.

 

[Blue Bear]

As a follow up..

Lake Speed Jr. and I exchanged a few emails concerning the rising fuel dilution value. He strongly recommended that I watch the video below. Lake Speed Jr.’s other gig involves piston rings. It makes since now, since I was a little shy on the initial break-in drives in Miss Daisy. I guess I need to get out and ‘let ‘er rip’ some, since I wasn’t near as aggressive as they are in the video. I hope this ends Miss Daisy’s fuel dilution issue, but I fear it won’t.

I don't think it's realistic to expect the break-in process to occur the way that they depict in the video. We are never the first people to start the engine and drive the vehicle. I don't recall how many miles my LC had on it when I picked it up, but it was more than 1 and less than 10. Once I picked it up, I had to drive it home for an hour on the highway. I did try to bed in the brakes almost immediately, but no way I could've done the engine break-in procedure exactly as they describe. I'm not shy about occasionally letting the engine work a little bit, but I may try to do a systematic approach like they describe with 8-10 pulls in short order. Not sure if it'll make a difference with 10,000+ miles on my LC.

 

[ultane]

I don't think it's realistic to expect the break-in process to occur the way that they depict in the video. We are never the first people to start the engine and drive the vehicle. I don't recall how many miles my LC had on it when I picked it up, but it was more than 1 and less than 10. Once I picked it up, I had to drive it home for an hour on the highway. I did try to bed in the brakes almost immediately, but no way I could've done the engine break-in procedure exactly as they describe. I'm not shy about occasionally letting the engine work a little bit, but I may try to do a systematic approach like they describe with 8-10 pulls in short order. Not sure if it'll make a difference with 10,000+ miles on my LC.

Well, for the sake of argument, I am going to assume Lake Speed Jr. knows a boat load more about engines than I do. He knows that my second oil sample that he analyzed was at ~4,400 miles. Yet, he still recommended that I view that video, and follow the instructions there in. I am going to follow his recommendations. I will post back with my next oil analysis.

 

[Blue Bear]

Well, for the sake of argument, I am going to assume Lake Speed Jr. knows a boat load more about engines than I do. He knows that my second oil sample that he analyzed was at ~4,400 miles. Yet, he still recommended that I view that video, and follow the instructions there in. I am going to follow his recommendations. I will post back with my next oil analysis.

I'm not suggesting that Lake Speed Jr. is wrong, just that it is unrealistic to expect that we can follow the procedure immediately upon procuring the vehicle. They are suggesting that the break-in procedure should happen at 0 miles, at least that's how I understood it. I would be curious to know if it makes any sense for the cam break-in at anything other than zero miles. Same for the ring break-in. I'm planning to follow the procedure for the ring break-in, but not the cams.

 

[kmershly]

As a follow up..

Lake Speed Jr. and I exchanged a few emails concerning the rising fuel dilution value. He strongly recommended that I watch the video below. Lake Speed Jr.’s other gig involves piston rings. It makes since now, since I was a little shy on the initial break-in drives in Miss Daisy. I guess I need to get out and ‘let ‘er rip’ some, since I wasn’t near as aggressive as they are in the video. I hope this ends Miss Daisy’s fuel dilution issue, but I fear it won’t.

I had never heard of Lake Speed Jr. prior to your post, but a quick Google indicated, he is the son of a NASCAR driver, he is an expert in lubrication, has worked for different NASCAR teams and is a YouTube Content Creator.

I rarely believe anything any "YouTuber" has to say, but in his case, he is an expert, so I will give him his due deference.

I also have absolutely no idea the processes that a Toyota goes through at the factory, so it is entirely possible that Toyota and BMW do things very differently.

With all that said, I have a close friend who is a Powertrain Engineer at BMWAG (BMW Germany) and he has taken me on a number of private tours of the BMW factories in Germany, he has also taken on me on a private tour of BMW Group Plant Spartanburg (where they build the BMW "X" vehicles SUVs).

At each of those plants, after the vehicle is finished being assembled, it goes through a number of tests and procedures including taking each vehicles through a number of acceleration/deceleration scenarios to start the break-in procedures of the engine and rings. He says that those procedures in the factory are generally enough to stop any oil dilution, but more should be done to ensure that the engines has the longest life possible.

After that, especially with the "M" cars, but all BMWs, BMW suggests varying speeds and varying RPM to ensure that the engine and rings break-in properly.

I have asked him how BMW Powertrain Engineers envision the process to accomplish that, he says that for the first 1,000 to drive the car in "manual" transmission mode to prevent the EGS (electronic gear shift, BMW speak for TCU) from seeking the highest gear possible for fuel economy and like the video accelerating and decelerating multiple times.

I sent him Lake Speed Jr. video and I got his typical German "yeah" response, which means good generic info, so take that for what it is worth.

I did ask him if he knew how Toyota does things at their plants, he responded beyond the Supra (which BMW builds for Toyota), NO.

Now, I followed the BMW break-in procedure on my LC by driving the car in "manual" transmission mode, accelerating and decelerating for the first 1,000 miles, I have not had an oil dilution issue since the break-in oil change at 1,200 miles.

 

[No15]

That's one of my concerns. Is the fuel dilution due to having low spring tension to increase the fuel mileage? If I continue to see the same dilution, then I'll probably start changing my oil more frequently than every 5K.

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

 

[ptahkeem]

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

A few things from what I’ve gathered:

-Reduce fuel dilution
-Remove any engine wear material
-Keep oil break down minimized which will come from several factors; condensation, acidification, molecule shearing, etc
-Help keep additive package numbers up to reduce engine wear

We have small displacement turbo engines so frequent oil changes, 5k miles(6 months) or less, are good for our engines. Frequent oil changes are good for all ice engines in general though.