Install real-time lubrication oil quality sensor

[juliansb]

I want to install an oil quality sensor (density + viscosity + temperature + humidity) to monitor online the lubrication the oil in my car (BMW series 3 E46), save the data and see the results online in my phone. A lab analysis tests many more parameters but those 4 are fine for me.

The tech part is solved as my company gave me the sensor for free and it uses standard communication protocols so there is no problem to get the data out. I still need to figure out what output rate is good as the default setting of 2 measurements per second do not make any sense and it will just take up storage space. Maybe 1 sample per hour would be a good figure to start with.

My idea is to test the oil in the can before changing the used oil and take save the sensor data while I use the car normally until the car computer says it’s time to change it (I believe it only counts the mileage) and see how it has degraded. I will in the meantime sample the old oil as I only need to wet the sensor in my table and ask in the forum about if it still good (maybe it just needs filtration) or not.
The problem and main reason for the post is to ask you if you have done something similar before (it can be any kind of sensor that required to be in contact with the oil) and how to mechanically attach the sensor to the car. I don´t need the oil to be flowing as the sensor does not care.

I have a screw version (1/2” gas fitting) but there is no way I will drill the oil pan:

This is the same sensor with a baseplate:

I could run the oil trough the baseplate, but in this case I would need to pump at least 1ml oil to the sensor (+ the oil to fill the tubbing) and pour it back into the car… if the tube fails the oil will be pumped out of the car!

There shall be some easier way to do it like bypassing the car original oil pump or inserting the sensor somehow in the place of the original oil level sensor (that is broken anyway) and use my sensor also as a level switch (as it would measure air when the oil is low)…

If someone can help me it would be a cool weekend project and later I could even add more units of the same sensor to monitor the fuel (the fuel where I live is good so really there is no need, power steering oil or the refrigeration water...) If it´s too complicated to install I will forget the project and try to find another use for the sensor.

Thanks!

 

[dparm]

Wow, great thread.

Doesn't the E46 already have something like this to monitor oil quality? My E90 does.

 

[juliansb]

The E46 seems to have only an oil level sensor but the E90 it does provide information on oil aging:

"BMW’s “Condition Based Service” (CBS) system monitors various maintenance items, and alerts you when service is needed. It is found on 2002 and newer 7 Series (E65 & E66), 2004 and up 1 Series (E87), 2004 and up 5 Series (E60 & E61) and 6 Series (E63 & E64), and 2006 and up 3 Series (E90 & E91)."

The E90 has a dielectric constant sensor, an economic method to screen out wrong oil, badly degraded or contaminated oil. It serves its purpose as a last line of defense for your engine.

See the explanation of how it works below:

"
The following system functions are described for the oil condition sensor:
- Measuring method
- Electronic oil level control

Measuring method
The oil condition sensor consists of 2 cylindrical condensers. The condensers are mounted above one another. 2 metal tubes are inserted one into the other to serve as electrodes. The engine oil is used as a dielectric medium between the electrodes.


Explanation of the terms 'dielectric' and 'permittivity':
A dielectric is defined as a non-conductive material in an electrical field. The electrical field is split by an insulator.
The permittivity (Latin: permittere = permit, let through) is also referred to as the dielectric conductance. The permittivity specifies the degree to which materials allow electrical fields to pass. The factor indicates by how much the voltage at a capacitor drops when a dielectric, non-conducting material is arranged between the capacitor plates.
"

Aditional info about how your car senses the oil condition:
Machinery Lubrication

 

[dparm]

That's correct, I actually mentioned it once before.

Keep us posted on how your install goes. Have you tried asking on the various BMW owner websites?

 

[SuperDave456]

Very cool stuff.

What type of oil filter housing does that BMW have?

I'd run a bypass baseplate from the oil filter to another location where the sensor and the filter would be. Yes there are more connections, and more possible points of failure, but that goes with any additional equipment that is added to a car.

Also, something to think about. Storage space these days is cheap. There cannot be that much data coming off of that thing, and 2 measurements a second isn't all that much. I'd leave it where it is and install it and see then what can be adjusted.

Shoot, you may be able to data mine your daily commute to work, second by second, and see where you could improve things.

Very interesting stuff.

 

[juliansb]

dparm, I was replying to you I have found the characteristics of you sensor:
BMW oil condition sensor

I have asked in BMW forums but there was no valid answer most people just said "why?". I was asking the wrong question.

SuperDave456, you got me on the right track. The oil filter housing in the E46 does not allows bypass but there is an expensive option, a remote filter block with sensor ports. But there is also a nice cheap alternative also for racers...an oil cooler adapter kit. $50 fot the adapter without a cooler and hoses:

"This kit replaces the oil cooler hard lines with two of -10 AN fittings, O-rings and a mounting bracket. Flexible braided hoses can then be run to the oil cooler adding many options for routing and provide more room in the engine compartment. The Kit only fits on E36 Euro oil filter housing and E46 M3 (S54 engine) oil filter housing, and compatible with COSMO Racing after market oil cooler and many others. Does not work with North American E36 stock oil filter housing and E46 M3 oil cooler."

Thanks, now I´m seeing it much more feasible.

About the data sampling rate, I want to have an normalized viscosity measurement at a reference temperature as they appear on the oil reference data and ASTM tests. Therefore the results are compensated with the temperature so I won´t see the reduction of viscosity of the oil as the engine heats up but the same results as the tests were performed in a lab. The data variation will be only due to the oil aging or contamination. So I would have too many samples with no change in value, a flat line considering only a short period of time.

I could even determine the cause of contamination as my sensor is quite precise:
- Density: 0.1% Full Scale
- Viscosity: 0.5% Full Scale
- Water activity: 0.5% Full Scale.
- Temperature: 0.2°C

If the humidity (water activity) goes up it can be that refrigerant or water is contaminating the oil. If the density/viscosity varies but the humidity does not it probably diesel whats contaminating the oil. I will get the help of the guys in the lab to help me interpret the sensor data.

If I was measuring fuel it gets more dynamic. My car is diesel so I can check density & viscosity specs of the fuel in real time against the European Norm to recognize what fuel is being used: Diesel, B100 (pure biodiesel), B80 (80% biodiesel/ 20% diesel) up to the fuel I sometimes use (good to clean the engine) the B20 (20% biodiesel/ 80% diesel). Note that BMW does not have certified the use of biodiesel in my car (they say that I can get a new fuel pump ready for biodiesel), so I use sometimes the most "weak" one.

For gasoline and diesel the idea would be the same, identify the fuel type, contamination and what is common in some countries like my home country, Brazil, the adulteration of the gasoline by adding more alcohol to the regular gasoline (it already has 20% ethanol by law)or in diesel things like adding soy oil mixed to the diesel, used lubrication oil or things even worst.

I appreciate any additional ideas and comments form the forum and I will post pictures and data of whatever I do. I have still almost 7000km/4340miles to go before the car asks politely for new oil. I will sample my current oil manually so you know its current state.

Thanks

 

[double vanos]

The E46 has a plastic oil filter cap. Should be inexpensive. Buy one and see if your sensor will fit in it somehow. Just a thought.....