Oil/Fuel Dilution Concerns...

[MustardTiger]

Just reading over at the Land Cruiser forum...seems like some owners have noticed fuel dilution (~4.5%) issues and associated rising oil levels on the dipstick with the 2.4 Max. Anyone here having this issue? I know for me, since new, every time I pull the dipstick...there is a strong gas smell. And I have noticed variations in oil level...and never lower than it was before. Thinking maybe with the hybrid being on/off...fuel dilution is happening. I recently changed my oil, had the level right at the full mark...and in a short time, I've driven a 6 hour highway trip, and maybe 60-75 miles city. The oil level is now 1/4 inch above the full mark, and smells like fuel/gas.

https://www.landcruiserforum.com/threads/fuel-dilution.4761/

Thoughts? Anyone else notice this on theirs?

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[MT-Taco]

I’ve owned several hybrids. Still own . If you make a lot of short trips it can be a problem. 20-30 minute trip at highway speeds once a week solves the issue. But the body on frame is an entirely different hybrid system, I thought I read some where tow/haul mode with the Tacoma Hybrid will keep the engine running at all times? Doing that a couple times a week would probably work to reduce the problem as well. I don’t own an iforce max but somebody will chime in?

 

[MustardTiger]

@MT-Taco yea I've started using the tow/haul mode to keep the engine running. Because as soon as the coolant in to operating temp...that engine shuts off at every opportunity it can. I can't see the oil getting to temperature for most short trips

 

[MT-Taco]

FYI Toyota dip sticks are not good, when I check my oil it’s always before the first drive of the day. I think it’s actually the tube that gets oil splashed into it?

 

[TacoFreak]

I think it’s actually the tube that gets oil splashed into it?

Yes. That common to many engines and it makes it really hard to see exactly what the oil level actually is.

 

[MustardTiger]

I definitely check the oil after it sits overnight, reading seems accurate to me. Maybe I need to tow a trailer with this truck, work it hard, really break it in. Idk.

 

[TimC.]

Fuel dilution is an engine killer if the engine has already broken in. Fuel pushes past the rings and into the oil. This is normal for a new engine as the rings form to the cylinder walls. Have your oil analysis done to confirm how much. Full break in can last up to 10k miles as oil analysis confirms wear metals. Last, do not baby the new engine. The rings must seat under load, not towing, but under rpm load range. This is the difference between wanting an engine to last for 150k miles or 300k plus miles. It's all about what you want.

 

[TacoFreak]

Fuel dilution is an engine killer if the engine has already broken in. Fuel pushes past the rings and into the oil. This is normal for a new engine as the rings form to the cylinder walls. Have your oil analysis done to confirm how much. Full break in can last up to 10k miles as oil analysis confirms wear metals. Last, do not baby the new engine. The rings must seat under load, not towing, but under rpm load range. This is the difference between wanting an engine to last for 150k miles or 300k plus miles. It's all about what you want.

This is very good advice, particularly for today's engines.

Oil analysis is really the only way to tell if too much fuel is getting into the oil. I agree that finding excess fuel in your oil once the engine is broken in is a big problem. Proper breakin is the way to get the best engine life possible, followed by regular oil changes and analysis.

 

[MustardTiger]

What would be an ideal break-in procedure? What would that look like?

For the first 800 miles or so I didn't really floor it, just drove moderate and normal. After that I have beat on it when given the opportunity...but those bursts of full rpm acceleration don't last long, for obvious reasons lol

 

[TimC.]

The idea here is to simulate a dyno pull.

1) Find a stretch of road with a straight and moderate up hill grade.

2) Put the truck in manual shifting and ease through 1st and 2nd at normal easy rpm.

3) Once you get into 3rd push the throttle down as you feel the load but not all at once and without stopping to you hit the floor.

4) Keep to the floor until you hit the red line slightly before and let off the gas all the way quickly and move shifter over to drive or in manual shift up 2 gears quickly.

This is a perfect dyno simulation.

 

[izzy]

We have port injectors and DI, I wouldn't worry about fuel dilution.

Seems to be mostly an issue with DI only vehicles.

In all honesty I don't hear the direct injectors on startup, only after the engine is done with cold-start process.

Which makes sense because vehicles go very rich on startup. This is when DI only approach has a major opportunity to dilute the oil. Gas ends up as a droplet no matter how much pressure you put through DI to atomize it. So when the engine is very rich on startup, you end up with this large quantity of fuel being directly injected into the cylinder not completely being burnt.

Port injection gas on the other hand is also partially atomized but the gas has to go a longer way past the intake valve, and the chances of washing the cylinder walls is fairly low even with a rich mixture for startup.

Dual injection no doubt made the T24A-FTS more expensive to manufacturer but it's clear Toyota knows DI only for turbo solutions is not the best approach.

 

[TimC.]

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.

 

[SnowmanJPS]

I’ve owned several hybrids. Still own . If you make a lot of short trips it can be a problem. 20-30 minute trip at highway speeds once a week solves the issue. But the body on frame is an entirely different hybrid system, I thought I read some where tow/haul mode with the Tacoma Hybrid will keep the engine running at all times? Doing that a couple times a week would probably work to reduce the problem as well. I don’t own an iforce max but somebody will chime in?

My Tacoma TRD Pro is warmed up before I get to the end of my street, it's literally the fastest warming vehicle I've ever owned, my street is 4km

 

[MustardTiger]

Last night changed my oil, got the level just below the full mark, and double checked/confirmed that level point first thing this morning after it sat all night. Today, went for 2 drives, city stop/go, in normal hybrid mode, then parked the truck back in the garage and left it sit for a couple hours. Just checked the oil...it's now showing overfull again. WTF !

 

[MT-Taco]

Check your oil every 1K. Change it at 4-5K, your letting your OCD get the best of you. My OCD is with squeaks and rattles

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