Oil/Fuel Dilution Concerns...

[SnowmanJPS]

I think this might be a case of it just being hard to read the dipstick, I usually flip my dipstick over and check, it looks overfilled on one side and fine on the other

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[MustardTiger]

@SnowmanJPS definitely aware the dipstick gives a different reading on each side, yes. Still easy to notice the increasing level

@MT-Taco yeaaa I know. I gave up checking the oil on my Ford 6.7 because it has the most impossible dipstick to read. As long as I put in the right amount at an oil change, there's no leaks, and any checks thereafter have oil on the dipstick...I drive it and don't worry about it lol. Just never had a vehicle before that noticeably got gas in the oil like this Taco. I'm going to start using my Carista OBD reader to see what the oil temperature is during driving, could be informative. Was hoping to be able to treat this truck the same as my old 5.7 Tundra...i.e. routinely change the oil every 8-10k kms and NEVER bother to check it in between, because I simply never had a reason to. I sure do miss that truck...

 

[MT-Taco]

@SnowmanJPS definitely aware the dipstick gives a different reading on each side, yes. Still easy to notice the increasing level

@MT-Taco yeaaa I know. I gave up checking the oil on my Ford 6.7 because it has the most impossible dipstick to read. As long as I put in the right amount at an oil change, there's no leaks, and any checks thereafter have oil on the dipstick...I drive it and don't worry about it lol. Just never had a vehicle before that noticeably got gas in the oil like this Taco. I'm going to start using my Carista OBD reader to see what the oil temperature is during driving, could be informative. Was hoping to be able to treat this truck the same as my old 5.7 Tundra...i.e. routinely change the oil every 8-10k kms and NEVER bother to check it in between, because I simply never had a reason to. I sure do miss that truck...

Yeah, I’m coming from a 2013 5.7 as well. I don’t do anything different with my 2.4T. I miss the V8 rumble but that’s about it.

 

[izzy]

True, however, we all have low tension piston rings. You get only 1 chance to break in the engine correctly, seat the rings. The piston rings and cylinder bore surface is where the engine life happens.

All great information and why I joined this community. I know this can get in the weeds but when you spend 70k for a truck you should do all you can for it.

Another point is all the engine recalls from Chevrolet and the Tundra. Chevrolet is hit with a massive engine failure due to crank shaft surface. So all the cats out here that think this is crazy talk, just go find a Chevy guy going through this.

In my opinion, the weakest link of the T24A-FTS is the open deck block. This will only become apparent for the guys trying to get a lot of power out of these via tuning.

Otherwise there's really not much to go wrong. It's one of the most simple gas turbo engines that's been put in a modern vehicle in a while.

When you compare it to the B48 (BMWs 2.0L 4 cyl turbo) it's caveman tech.

How many of these trucks aren't going to break in properly? Probably not many and the few that didn't, won't be burning excessive amounts of oil until 100,000 miles+

 

[LincolnSixAlpha]

Cylinder wash-down is a thing... Especially more so for you hybrid owners. That's fuel sprayed into the cylinder and not fully burnt. Per the comments, short trips where the engine is not fully warming up. Definitely a thing. Car Car Nut on Youtube had a Toyota in the shop for that. Older model, non-hybrid. If your interested:

 

[LincolnSixAlpha]

In my opinion, the weakest link of the T24A-FTS is the open deck block. This will only become apparent for the guys trying to get a lot of power out of these via tuning.

Otherwise there's really not much to go wrong. It's one of the most simple gas turbo engines that's been put in a modern vehicle in a while.

When you compare it to the B48 (BMWs 2.0L 4 cyl turbo) it's caveman tech.

How many of these trucks aren't going to break in properly? Probably not many and the few that didn't, won't be burning excessive amounts of oil until 100,000 miles+

I think your comments are spot on in my opinion as well. B48 garbage anyhow. BMW went down hill with suffing that 4-banger in most of their cars, replacing their six's. That said, I think T24A-FTS will last quite a long time with most of the owners.

Per your comments. I agree about the open deck, and unfortunately we are all dealing with low tension rings in all of these cars these days, so that's also another concern on my part. That and carbon buildup on the oil control ring. However thankfully this engine also has port injection so that should keep the garbage washed out of the cylinders.

Just remember, the old "Italian tune-up" will keep your engine clean engine especially if you baby it all the time. My 2 cents worth.

 

[izzy]

B48 garbage anyhow

I think the core engineering of the B48/58 is fine, it's just all the supporting stuff that ages poorly (usually the turbo coolant lines). By ages poorly I mean you'll have leaking hoses at 100,000 miles/10 years.. which I mean wouldn't surprise me on any engine.

And BMW owners aren't known for doing preventative maintenance or opening their hood at all, to be honest. Enthusiasts aside of course.

How Toyota got away with only PCV and cats as the emissions equipment on the T24A-FTS is also very impressive.

No EGR, no secondary air pumps, just PCV and cats.

I don't know how they did it lol

 

[Franko Manini]

Folks,

I drive a 2024 Trailhunter with the iForce-MAX hybrid engine. My plan was always to do used oil analysis (UOA) at least during the warranty period and to verify that the engine was broken in (by observing the decline of wear metals in the oil samples).

My first oil change was at 1,700 km (about 1,050 miles) and because it was the break-in oil change and I knew silicon and wear metals would be very high, I didn't bother to submit a sample for UOA. My second oil change was done at 7,769 km (4,827m) and I sent a sample off for UAO. The analysis came back with relatively high wear metals and very high silicon (from casting release and sealants), both of which I was expecting. What surprised me was that the fuel dilution was >5%. According to the SAE, anything over 2% should be considered problematic. The analysis was conducted by gas chromatography (GC), and it's sensitivity is limited to 5%. It cannot quantify anything greater. GC is considered the gold standard for detecting fuel in oil, but a lot of labs use flashpoint analysis. It's less accurate but can give you an approximation of the %fuel in the oil.

The oil in this sample was diluted so much that it was slightly below the grade range specified for that oil by API and SAE (SAE standard J300). I calculated when my next oil change should be based on that data and figured I should at least pull a sample in about 4500km.

I figured this whole issue might be anomaly and I was expecting the sample to look better on my latest sample at 12,000 km (7,456m). I took a sample but didn't do an oil change. The results still showed a >5% dilution, but wear metals and silicon were both coming down nicely. After seeing the result I changed my oil at 12,533km (7,788m) and made an appointment with the dealership having two data points to discuss.

I anticipate pulling my third sample at my next oil change which will be at 16,000km (9,941m). For this oil fill I've implemented a few driving/operating behviour modifications to help limit the fuel dilution.

I am trained as a scientist so I've dug in deep to the data and results that the UOA has provided, and I have a whole saga of what the dealership did and said, plus, I've studied a lot about how and why GDI engines, and in my particular case, hybrid engines have fuel dilution issues and what to do about it.

This post is already long, so If anyone's interested, I can add posts about:
-my dealership interactions
-causes of fuel dilution
-oil chemistry and how it influences fuel dilution
-how fuel dilution is measured and calculated
-practical actions you can take to combat fuel dilution

This is not my area of study, but I'm a half decent researcher and I've used data to inform my decisions and actions, all of which I'm willing to share if it won't bore people!

 

[lauren01]

Rest assured it will not bore this person. After working with engineers for 38 years as their business person, I have a keen interest in all things involving analysis and tinkering.

Please post at will. Thanks so much in advance for your shares on this topic.

 

[izzy]

Folks,

I drive a 2024 Trailhunter with the iForce-MAX hybrid engine. My plan was always to do used oil analysis (UOA) at least during the warranty period and to verify that the engine was broken in (by observing the decline of wear metals in the oil samples).

My first oil change was at 1,700 km (about 1,050 miles) and because it was the break-in oil change and I knew silicon and wear metals would be very high, I didn't bother to submit a sample for UOA. My second oil change was done at 7,769 km (4,827m) and I sent a sample off for UAO. The analysis came back with relatively high wear metals and very high silicon (from casting release and sealants), both of which I was expecting. What surprised me was that the fuel dilution was >5%. According to the SAE, anything over 2% should be considered problematic. The analysis was conducted by gas chromatography (GC), and it's sensitivity is limited to 5%. It cannot quantify anything greater. GC is considered the gold standard for detecting fuel in oil, but a lot of labs use flashpoint analysis. It's less accurate but can give you an approximation of the %fuel in the oil.

The oil in this sample was diluted so much that it was slightly below the grade range specified for that oil by API and SAE (SAE standard J300). I calculated when my next oil change should be based on that data and figured I should at least pull a sample in about 4500km.

I figured this whole issue might be anomaly and I was expecting the sample to look better on my latest sample at 12,000 km (7,456m). I took a sample but didn't do an oil change. The results still showed a >5% dilution, but wear metals and silicon were both coming down nicely. After seeing the result I changed my oil at 12,533km (7,788m) and made an appointment with the dealership having two data points to discuss.

I anticipate pulling my third sample at my next oil change which will be at 16,000km (9,941m). For this oil fill I've implemented a few driving/operating behviour modifications to help limit the fuel dilution.

I am trained as a scientist so I've dug in deep to the data and results that the UOA has provided, and I have a whole saga of what the dealership did and said, plus, I've studied a lot about how and why GDI engines, and in my particular case, hybrid engines have fuel dilution issues and what to do about it.

This post is already long, so If anyone's interested, I can add posts about:
-my dealership interactions
-causes of fuel dilution
-oil chemistry and how it influences fuel dilution
-how fuel dilution is measured and calculated
-practical actions you can take to combat fuel dilution

This is not my area of study, but I'm a half decent researcher and I've used data to inform my decisions and actions, all of which I'm willing to share if it won't bore people!

Wonder if this has anything to do with the more frequent cold start cycles that hybrids do. Cold start = rich mixture + short engine cycle because hybrid = lots of gas in oil.

 

[MustardTiger]

@Franko Manini Please post your thoughts and findings!! This is why owner forums are so incredibly valuable. I need to research some oil sample test labs that are accessible, and get an idea what my numbers are.

I'm currently at 3,458 kms on the ODO...and at this point i've changed the oil in my truck like 3 times, at least. My initial change was around 850 kms and it was rank of gas, very thin, and had a metallic sheen. There has always been a gasoline smell on the dipstick whenever checking the oil. And now since the weather has turned colder, I have been noticing the oil level increase. My concerns are with viscosity shearing, as you indicated. I really think this engine, especially in hybrid form, warrants using one grade heavier oil, to help mitigate the effects on viscosity grade shearing from dilution. I've been researching the kinematic viscosity ratings (40c and 100c) of various oils to find a suitable option. Seems like Pennzoil Ultra Platinum 5w30 is a "thin" 5w30 oil, and will probably work well. It's just a brand I've never used, more of a Mobil 1 fan here. I'm thinking the M1 AFE 0W30 is also a good candidate. One has to be careful with some 5w20 oils as they appear, by the specs, to have a lighter kinematic viscosity ratings than some 0w20 oils...

Anywho, not trying to start an engine oil pissing match here...lol. The concern at hand is oil dilution!

 

[MT-Taco]

@Franko Manini Please post your thoughts and findings!! This is why owner forums are so incredibly valuable. I need to research some oil sample test labs that are accessible, and get an idea what my numbers are.

I'm currently at 3,458 kms on the ODO...and at this point i've changed the oil in my truck like 3 times, at least. My initial change was around 850 kms and it was rank of gas, very thin, and had a metallic sheen. There has always been a gasoline smell on the dipstick whenever checking the oil. And now since the weather has turned colder, I have been noticing the oil level increase. My concerns are with viscosity shearing, as you indicated. I really think this engine, especially in hybrid form, warrants using one grade heavier oil, to help mitigate the effects on viscosity grade shearing from dilution. I've been researching the kinematic viscosity ratings (40c and 100c) of various oils to find a suitable option. Seems like Pennzoil Ultra Platinum 5w30 is a "thin" 5w30 oil, and will probably work well. It's just a brand I've never used, more of a Mobil 1 fan here. I'm thinking the M1 AFE 0W30 is also a good candidate. One has to be careful with some 5w20 oils as they appear, by the specs, to have a lighter kinematic viscosity ratings than some 0w20 oils...

Anywho, not trying to start an engine oil pissing match here...lol. The concern at hand is oil dilution!

I ran pennzoil ultra platinum 5w30 this summer. Only thing I noticed was a quieter engine. Back to pennzoil up 0w20 for the winter.

 

[TimC.]

Here is my last two changes. Notice the first change was 396 miles, column to the right. Fuel dilution much better and contributed to proper driving to seat the rings.

 

[Franko Manini]

Wonder if this has anything to do with the more frequent cold start cycles that hybrids do. Cold start = rich mixture + short engine cycle because hybrid = lots of gas in oil.

That's definitely part of the issue, but oddly enough, my research indicates that idling does more harm. So shutting off the auto start/stop on your hybrid (for example by engaging Tow/Haul mode) and idling more, probably doesn't help. I say probably because I'm not completely done my research and testing on this. It's only a theory right now.

 

[Franko Manini]

@Franko Manini Please post your thoughts and findings!! This is why owner forums are so incredibly valuable. I need to research some oil sample test labs that are accessible, and get an idea what my numbers are.

I'm currently at 3,458 kms on the ODO...and at this point i've changed the oil in my truck like 3 times, at least. My initial change was around 850 kms and it was rank of gas, very thin, and had a metallic sheen. There has always been a gasoline smell on the dipstick whenever checking the oil. And now since the weather has turned colder, I have been noticing the oil level increase. My concerns are with viscosity shearing, as you indicated. I really think this engine, especially in hybrid form, warrants using one grade heavier oil, to help mitigate the effects on viscosity grade shearing from dilution. I've been researching the kinematic viscosity ratings (40c and 100c) of various oils to find a suitable option. Seems like Pennzoil Ultra Platinum 5w30 is a "thin" 5w30 oil, and will probably work well. It's just a brand I've never used, more of a Mobil 1 fan here. I'm thinking the M1 AFE 0W30 is also a good candidate. One has to be careful with some 5w20 oils as they appear, by the specs, to have a lighter kinematic viscosity ratings than some 0w20 oils...

Anywho, not trying to start an engine oil pissing match here...lol. The concern at hand is oil dilution!

There's lots to unpack here. I'll chime in on what I can help with.

It's expected that your oil will be thin, have fuel contamination, and metallic content during the first say 1600km (1000m). I'm not surprised at all. This is when most of the wear your engine will ever see occurs. During the break-in period.

Fuel dilution will increase as the temperature decreases. This is due to a number of factors, which I may go into more detail on in a future thread. They are: slower vaporization rate of gasoline as it enters the cylinder, thermal deformation of pistons relative to cylinders, and the time it takes to engine oil to reach operating temperature (80-100C). Some people may have no issues at all with fuel dilution if they live in a warm climate.

Viscosity shearing is not what's negatively affecting your oil. Shearing is where the viscosity modifiers (very specialized chemistry that is designed to increase the viscosity of the oil as it gets hotter) are physically SHEARED and no longer can perform their function. These molecules actual unwind and take up more space as they get hot. They prevent to oil from thinning out too much as it warms up. Timing chains are a big source of shear wear. If you're concerned about shear wear look at the HTHS (high temp/high shear) testing values for given oils.

One must be careful using a grade of oil other than what is specified for the engine. if you want to try it (and I will be in the future), I suggest focusing on the winter grade value (the "W" part of the viscosity range. Fuel dilution is really only an issue when the engine is below operating temperature. This has very little to do with coolant temperature an everything to do with oil temperature. Just because your coolant is at 80C, doesn't mean your oil is. In fact, in my test, oil temp takes quite a long time to reach 80C and above, and requires a fair bit of time (say 30 minutes) or considerable load on the engine. I may get into why 80C is the magic number in a future thread if anyone is keen. But the W number is important. Toyota likely runs 0W oil fortwo reasons: 1) to ensure the engine starts easily in VERY cold weather (think -45C) and 2) to improve corporate average fuel efficiency numbers. Going down the grade scale by one grade can increase fuel efficiency by between 0.2% and 0.4% which seems like a small amount, but in an ICE engine that is likely only 40% efficient, it's a huge deal.

Back to why focus on the W aspect of the multiviscosity oil...

Firstly, fuel dilution is MUCH worse at low temps so that's the end of the scale we want to modify. Secondly, if you go up a grade you're exposing the oil to a viscosity range that it already sees within the manufacturer recommended oil. Meaning, 0W-20 "contains a range of grades, between 0 and 20. So introducing say a 5 weight oil isn't an issue. It won't offer more protection to fuel dilution. That comes from chemicals in the oil called dispersants. Any oil with API-SP rating will have a butt load of dispersants. It may REDUCE fuel dilution because it will form a stronger film between cylinder bore and piston rings when the engine is cold as compared to 0W. When an engine is cold, the parts don't fit together properly. They all have clearance values determined by the engineers, and those clearances are wider when the engine is cold. All metals expand (albeit at different rates) when they warm and the engine is designed to run at operating temp (80C+). A 5W oil will provide strong er film strength at startup and may reduce fuel dilution as a consequence. 5W is rated for-40C (this spec published in SAE J300 if you want to look it up) and 0W is rated to -45C. So unless you live somewhere REALLY cold, 5W-20 should be fine. Even the owners manual says you can run it (but you should change it back to 0W-20 when you can).

If you go up to XW-30, you're introducing an oil viscosity range that the engine wasn't designed for. Remember those clearances I talked about? They could be too tight to allow adequate film formation with your 30 weight oil in some journals or bearing surfaces. I suggest you steer clear of increasing that end of the range.

Sorry for rambling on, but I hope this helps you work out your plan of action.

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