Lexus Vehicle Health Report - Engine Oil Quality Parameter

[The Critic]

I have a 2025 Lexus TX500h with the T24A-FTS. In the vehicle health report, there is an "engine oil quality" parameter:

I changed the oil and filter at 1000 miles so the current fill has about 1600 miles. I am curious how the vehicle is measuring engine oil quality. Does anyone know?

 

[fantastic]

A dummy timer that changes with miles? A sensor that reflects light to see how dirty the oil is? I'm curious too.

 

[Rand]

There is a code for the sensor

OBD-II fault code P252D​

So it must actually use some type of sensor?
probably relates to contamination more than anything.
It should be renamed "engine oil cleanliness"

 

[JohnnyG]

Too much speculation. Oil color means nothing.

 

[BiggerBreakerBar]

Most OLMs are a math function of engine hours / environment / load, not physical sampling. Like a slightly fancier version of "next change in 3k" sticker.

Y

Thread 'OLM Accuracy'

Sep 19, 2017

2014 IS350, manual says 10,000 mile OCI, but my light usually comes on around 5k no matter what oil I use. This got me wondering how accurate the monitor actually is, Lexus OLM information states:

Quote:
"Smart technology, like the Oil Life Monitor (OLM) system, automatically monitors the oil life in your vehicle using an advanced algorithm, on board computer system that alerts owners when it’s time for an oil change, so they can address the issue promptly and without hassle. When the dashboard light is triggered, indicating “OIL MAINTENANCE REQUIRED,” all the owner has to do is schedule...

• Youthanasia
• Replies: 35
• Forum: Passenger Car Motor Oil (PCMO) - Gasoline Vehicles

 

[Titan]

There is a code for the sensor

OBD-II fault code P252D​

So it must actually use some type of sensor?
probably relates to contamination more than anything.
It should be renamed "engine oil cleanliness"

Don't know about Lexus, but I copied this from a BMW source: "The oil sensor, called “OZS” by BMW, uses the lower capacitor to measure the oil quality and the upper capacitor is used to determine the oil level. The sensor measures the dielectric value of the oil against a dielectric constant (value) to determine the contamination level of the oil."

 

[kschachn]

Of little help, but this discussion mentions an oil quality reading CEL. Perhaps a general Internet search of this particular vehicle system may help:

S

Thread 'Alternative oil for the tropics'

Aug 21, 2025

Hi so I have come across this site in the exhaustive search looking for answers and hopefully guidance.
A little background - I am originally from the UK and own a UK spec 2021 Ford Ranger Wildtrak 2.0L 213PS Biturbo Diesel Auto with DPF and wet belt with 12k on the clock.
I have relocated to the Caribbean (Trinidad & Tobago) on an electrical contract and decided to take my vehicle with me. I have always serviced with Ford and gave her a full service before plonking into the container. After 7 months of being here my engine light has flashed up and after a Forscan check I was greeted with...

• Scottie365
• Replies: 26
• Forum: European and Import Motor Oils

 

[MolaKule]

"The OPS3 multi-parametric oil quality sensor is designed for oil condition monitoring and preventative maintenance of critical machinery. Relying on tuning fork technology, the sensor monitors multiple physical properties that enable the system to determine the quality, condition and contaminant loading of fluids such as engine oil, transmission, hydraulic and gear oils. The multi-parametric analysis capability improves fluid characterization algorithms. The OPS3 provides in-line and continuous monitoring of fluids for a wide range of OEMs and aftermarket installations, including process lines and pressurized high flow conduits (e.g., engine oil gallery)..."

https://www.te.com/en/product-CAT-FPS0010.html

possibly derived from this technical paper:

https://pmc.ncbi.nlm.nih.gov/articles/PMC10146063/

 

[chris719]

"The OPS3 multi-parametric oil quality sensor is designed for oil condition monitoring and preventative maintenance of critical machinery. Relying on tuning fork technology, the sensor monitors multiple physical properties that enable the system to determine the quality, condition and contaminant loading of fluids such as engine oil, transmission, hydraulic and gear oils. The multi-parametric analysis capability improves fluid characterization algorithms. The OPS3 provides in-line and continuous monitoring of fluids for a wide range of OEMs and aftermarket installations, including process lines and pressurized high flow conduits (e.g., engine oil gallery)..."

https://www.te.com/en/product-CAT-FPS0010.html

possibly derived from this technical paper:

https://pmc.ncbi.nlm.nih.gov/articles/PMC10146063/

I don't think the ones that are used in passenger cars are this fancy. These are pretty expensive, probably for industrial or trucks / fleet.

 

[JohnnyG]

Wow, imagine that. No more need for UOA's, "my tuning fork says it's fine"!

 

[dogememe]

Wow, imagine that. No more need for UOA's, "my tuning fork says it's fine"!

Perhaps you can put the motor oil in crystal singing bowls to extend its lifespan? We can see what frequencies resonate the best with 0W-20 vs 5W-30?

 

[JRay’07]

I wonder how much the dielectric value for new lubricants varies. Does the system which monitors this sensor become inaccurate if one were to deviate from the manufacturer’s recommendation?

 

[BiggerBreakerBar]

The BMW spiel suggests a reference against a standard to as the trigger.

What can these dielectrics sensors actually monitor - is it a conductivity test? Does that mean PH and/or metallic solids, perhaps?

 

[kschachn]

What can these dielectrics sensors actually monitor - is it a conductivity test? Does that mean PH and/or metallic solids, perhaps?

Good question. Conductivity, pH, and solids are all different properties and different measurements.

 

[f355spider]

I would ask the Lexus dealer service advisor, or shop foreman.

 

[OVERKILL]

I have a 2025 Lexus TX500h with the T24A-FTS. In the vehicle health report, there is an "engine oil quality" parameter:

View attachment 300002
I changed the oil and filter at 1000 miles so the current fill has about 1600 miles. I am curious how the vehicle is measuring engine oil quality. Does anyone know?

Would be interesting to see if this changes, that if resetting the OLM changes it at all; ie, does resetting the OLM (which has historically been a mileage counter for Toyota) also reset this "Oil quality" parameter, or is it actually sensor derived like BMW has been doing for ages?

 

[bbhero]

Wow, imagine that. No more need for UOA's, "my tuning fork says it's fine"!

I don’t care who you are… that’s pretty darn funny right there …

 

[JRay’07]

This thread reminded me of this device from several years ago.

 

[Hohn]

Too much speculation. Oil color means nothing.

Well obviously it means *something*, the problem is coming up with a valid interpretation of that meaning.

 

[BMWTurboDzl]

I have a 2025 Lexus TX500h with the T24A-FTS. In the vehicle health report, there is an "engine oil quality" parameter:

View attachment 300002
I changed the oil and filter at 1000 miles so the current fill has about 1600 miles. I am curious how the vehicle is measuring engine oil quality. Does anyone know?

It probably uses a sensor similar to what BMW and others have been using for over a decade. It calculates a dielectric value of the oil and compares it to reference value.