Oil/Fuel Dilution Concerns...

[TacoFreak]

yeah, no off button on a hybrid. The hybrid system controls the ICE and other than using tow/haul mode you are out of the loop.

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[MustardTiger]

Gas in oil. Overfull crankcase. This isn’t normal. I’ll never be able to go a full OCI in the winter…

 

[Rocko]

Gas in oil. Overfull crankcase. This isn’t normal. I’ll never be able to go a full OCI in the winter…

Did you check it when cold. Mine did the same thing when hot, and when I rechecked it in the morning, it was normal. Now when I change the oil, I try to get it 3/4 full and call it good.

 

[MustardTiger]

@Rocko yeah I always check it cold, and multiple times. I just don't understand what this engines problem is! Maybe it has something to do with the excessively high fuel consumption during cold weather? It chugs gas on the highway as bad or worse than my 5.7 Tundra ever did...yet with half the cylinders, the end result is gas in the oil. Idfk anymore. Last thing I want to do is waste my time visiting the dealer...they won't do anything or even acknowledge it as a problem

 

[TacoFreak]

It chugs gas on the highway as bad or worse than my 5.7 Tundra ever did...yet with half the cylinders, the end result is gas in the oil. Idfk anymore. Last thing I want to do is waste my time visiting the dealer...they won't do anything or even acknowledge it as a problem

Yeah, I don't think the dealer will do anything about this. But my last truck was a 5.7L Tundra and my 4th gen gets a lot better mileage than it ever did. That makes me think that there really is something wrong with your truck. Good luck and keep us posted.

 

[MustardTiger]

This is a screenshot of my live engine data, driving highway speeds in -13f (-25c) temps, taken 1 hour into trip, burning regular 87 (10% ethanol). Engine oil temperature is simply too low (185f). My dad was driving his 5.7 hemi ram in same conditions, his engine oil temperature was 210-212f (99-100c), same conditions, same gas.

No wonder my engine gets gas in the oil during the winter…it can’t run hot enough in the cold temps

 

[izzy]

This is a screenshot of my live engine data, driving highway speeds in -13f (-25c) temps, taken 1 hour into trip, burning regular 87 (10% ethanol). Engine oil temperature is simply too low (185f). My dad was driving his 5.7 hemi ram in same conditions, his engine oil temperature was 210-212f (99-100c), same conditions, same gas.

No wonder my engine gets gas in the oil during the winter…it can’t run hot enough in the cold temps

Interesting, even in temps 45-50, the engine oil takes it's sweet time to climb up to 195-200F, like 10 miles of freeway driving minimum.

You really need at least 195F to start burning moisture out of the oil.

185F oil temp is just too low.

 

[MustardTiger]

An update on this issue.

Was recently at a Toyota dealer getting an oil filter, and asked to speak to the service manager. He sent a senior tech out to chat with me regarding the oil dilution issue I have been experiencing during extreme cold operating temps. After sharing my details, he didn’t deny the issue, and said it’s a product of the high thermal efficiency of the engine, and direct injection - and that it’s a common issue across all makes. He felt my engine oil temperature during highway cruising was too low, and recommended that I fabricate some kind of winter front for when the temperatures are extreme - even though the truck has “grill shutters”. He commended me for monitoring the oil level, and sucking out/topping off to keep it within spec and prevent wear…as most people would never do that. He did talk about what he considers “significantly overfull” for the crankcase, and also commented that he personally runs “thicker than spec” grade in all his vehicles. I didn’t comment on that, wink wink.

They were having a Toyota Engineer visiting the next day, and was going to ask him about this issue and get his thoughts. But he said with the v35 issues, the Toyota Engineer may not have time - but he’ll ask. I don’t plan to follow up because literally there is no resolution from Toyota, as it’s an isolated issue/phenomenon - I’m on my own here. I may look at seeing if there is a way to partially block the front of the truck during extreme cold temps, maybe something discrete around the fog lights and lower bumper. One thing I might try first is removing the air filter box primary intake funnel, that goes over the radiator support and seals against the hood. Four clips and it’s out of the way and not directing cold air in from the front. Idk. All I want is to not have to worry about this problem in the winter.

 

[izzy]

An update on this issue.

Was recently at a Toyota dealer getting an oil filter, and asked to speak to the service manager. He sent a senior tech out to chat with me regarding the oil dilution issue I have been experiencing during extreme cold operating temps. After sharing my details, he didn’t deny the issue, and said it’s a product of the high thermal efficiency of the engine, and direct injection - and that it’s a common issue across all makes. He felt my engine oil temperature during highway cruising was too low, and recommended that I fabricate some kind of winter front for when the temperatures are extreme - even though the truck has “grill shutters”. He commended me for monitoring the oil level, and sucking out/topping off to keep it within spec and prevent wear…as most people would never do that. He did talk about what he considers “significantly overfull” for the crankcase, and also commented that he personally runs “thicker than spec” grade in all his vehicles. I didn’t comment on that, wink wink.

They were having a Toyota Engineer visiting the next day, and was going to ask him about this issue and get his thoughts. But he said with the v35 issues, the Toyota Engineer may not have time - but he’ll ask. I don’t plan to follow up because literally there is no resolution from Toyota, as it’s an isolated issue/phenomenon - I’m on my own here. I may look at seeing if there is a way to partially block the front of the truck during extreme cold temps, maybe something discrete around the fog lights and lower bumper. One thing I might try first is removing the air filter box primary intake funnel, that goes over the radiator support and seals against the hood. Four clips and it’s out of the way and not directing cold air in from the front. Idk. All I want is to not have to worry about this problem in the winter.

Thick cardboard with removable zipties holding it to the grille? Maybe even black cardboard if you wanna get fancy with it.


These run very cool, glad to see that is confirmed by Toyota to some degree. Guys wanting to bolt on trans coolers need to be careful because their transmission will never reach operating temp with an external cooler lol

 

[32spoke]

Direct injection and thermal efficiency… ain’t buying it…. Test the old oil for fuel and water contamination. Cold climates cause condensation on cold starts- water emulsifies with the oil…. Just a suggestion, but get it tested..

 

[32spoke]

Thick cardboard with removable zipties holding it to the grille? Maybe even black cardboard if you wanna get fancy with it.


These run very cool, glad to see that is confirmed by Toyota to some degree. Guys wanting to bolt on trans coolers need to be careful because their transmission will never reach operating temp with an external cooler lol

Transmission oil temps creep up during off roading at low speed in 4wD-hi, likely from the torque converter…not in lock up…. And the too cold of fluid has been addressed by Hayden since the early 1990s.
https://www.haydenauto.com/en/produ...oil-coolers/patented-internal-by-pass-coolers

 

[TimC.]

You have done a lot of good work here to document the issue. Let's be clear, the only way fuel is getting in the oil crankcase is by the piston rings. This engine is not sealed up. Go to Speed Diagnostics and order a oil analysis kit and start your scientific data collection to prove the issue likely in court. There is no way you can ever lubricant the engine properly with this much fuel dilution. This is not normal by any stretch. You have a lot of money on the line and proper and intelligent data will prove your case. I will be glad to help you offline if you want.

 

[izzy]

Transmission oil temps creep up during off roading at low speed in 4wD-hi, likely from the torque converter…not in lock up…. And the too cold of fluid has been addressed by Hayden since the early 1990s.
https://www.haydenauto.com/en/produ...oil-coolers/patented-internal-by-pass-coolers

True there are solutions for the under-operating temp issue.

Mishimoto model though which has been paraded around this forum and touted as the best solution is just not it. https://www.mishimoto.com/transmission-cooler-toyota-tacoma-2024.html?

It's too big, doesn't have a bypass or thermostat, and is too expensive for what it is.

>Let's be clear, the only way fuel is getting in the oil crankcase is by the piston rings.

100% loosey goosey rings + piss thin oil + not getting up to temp = a ton of fuel getting into the crankcase.

Terrible combo to be honest.

I've not seen any dipstick rising but, I do go out of my way to drive further than I need to for errands, to ensure my oil temp gets up to 180F+. I also frequently do non stop freeway driving for 30 miles at a time where the oil temp is at 200F+.

OP could just get the longest powertrain warranty they can find and then ride it out and sell the truck when it expires. Maybe it's not been long enough to damage anything but fuel in the oil doesn't help your bearings, cams, lifters etc anything idk I'd be sus

 

[32spoke]

True there are solutions for the under-operating temp issue.

Mishimoto model though which has been paraded around this forum and touted as the best solution is just not it. https://www.mishimoto.com/transmission-cooler-toyota-tacoma-2024.html?

It's too big, doesn't have a bypass or thermostat, and is too expensive for what it is.

The viscosity of the oil can be the bypass mechanism, such as the Hayden trans oil cooler link I sent.. @Mishimoto may have an opinion about their cooler and how it may or may not harm the transmission… or why they chose not to add a thermal bypass valve..

 

[MustardTiger]

Direct injection and thermal efficiency… ain’t buying it…. Test the old oil for fuel and water contamination. Cold climates cause condensation on cold starts- water emulsifies with the oil…. Just a suggestion, but get it tested..

The T24A has a thermal efficiency rating of around 38%...which is pretty high for a mainstream modern engine. Not many engines surpass 41-42%. I want to make it clear, my truck ONLY dilutes during extreme cold conditions....which is -25c and below (-13f). The colder it is from there, the worse it seems to dilute (and probably condensate too). Except for the fringe areas of the northern states...many Tacoma's in the mainland US are not going to be exposed to these type of extreme cold operating conditions, or very briefly if they are. Those who are in the northernmost border states, the prairies of Canada, northern Canada, and parts of Alaska...will be operated, at times, during extreme cold, and need to watch carefully for oil dilution. Otherwise, in normal temperatures...this is NOT an issue. I don't have loosey goosey rings lol, and the engine is not failing. Also to note...this is an issue I've read about at length (i.e. oil level increasing on the dipstick), over on comparable Rav4 forums, regarding the A25 engine. I've also read about this issue with the new Land Cruiser...and I'm sure we'll soon see some 6th gen 4Runner owners in the north bring the issue forward as well.

I truly believe the issue is compounded by several factors:

-intake air temperature low (-20f and below during extreme conditions)
-ambient air temperature low (-20f and below in extreme conditions)
-oil temperature low (180-185f)
-minimum threshold achieved for engine coolant temperature (175-180f)
-direct fuel injection experiencing less atomization of the gas, due to all these extreme cold metrics (especially the low intake air temperature)
-extreme cold temperatures will naturally yield less efficiency, thus higher engine load (i.e. burning more gas)
-E10 gasoline that contains/attracts more water, and is less efficient (thus a need for increased engine load, more boost, and resulting higher concentration of condensation)
-0W20 oil and low tension piston rings
-minimal shielding on the front of the vehicle, other than the grill shutters that (should be closing). However that is a relatively small section of the radiator/condenser area anyways

I think the best thing someone can do is monitor the oil level during cold operating conditions (say -13f and below). If it gets too high (say 1/2 inch above full mark) and you're nowhere near due for an oil change, you need to vacuum the oil down to the add mark, and top it off with fresh oil. Keep in mind, if you are choosing to stick with the Toyota recommended 0w20 grade oil...when it gets 1/2 inch above the full mark...you are approaching near 5% fuel diluted oil and that 20 weight oil is now sheared down to a 15 or 10. It is simply not ok to keep running it like this, especially if it keeps increasing during extreme cold conditions. I have moved to a 5w30 grade, and will run that all year/all seasons. My reasoning is that there is always going to be a certain % of fuel in the oil, higher in the winter, lower to almost none in the summer. The 30 weight grade will more than likely shear down to a 20 weight grade anyways. I'd rather have that, then a 0w20 shearing down to a 15 or 10 weight grade and causing actual engine wear/damage while I cluelessly zoom around in my Tacoma. This is the best compromise I can come up with, with my next action to block off sections of the front of the truck. I just don't want it to look stupid. As a diesel truck owner, one winter I got lazy and didn't put my winter front on the truck. On a 5 hour road trip in -30f temps with a nasty wind...the diesel fuel started to gel up and the engine cut out. Luckily I had a jug of Diesel 911, dumped that in, and a pair of Carhartt work pants in the back seat. Those work pants got strapped across the grill, and I was able to make it home. So...I definitely know cold. Just never had any "winter" issues before with a gas vehicle.

I would get an oil sample analysis done, however there is absolutely no place convenient or cheap in my area of western Canada. Blackstone or Speed is not an option.

Anyways, feel free to roast me for what I've wrote above, as you see fit

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