I posted this in the Roadster section as a response to another thread but figure many will miss it. This is quoted directly from the Crossfire Student Reference Book:


Oil Sensor
To produce an accurate determination of required oil change intervals, the Crossfire uses a sophisticated three-part oil sensor. It is used as part of the Flexible Service System (FSS). Calculations (such as oil level and time to next oil change) performed by this system can be observed in the vehicles odometer.
The oil sensor is located on the right side of the engine oil pan. The oil sensor uses a three-wire circuit, 5-volt VREF, ground and a 5-volt digital signal circuit. The oil sensor contains three sensors that act as one. It contains sensing components and circuitry to determine the level, temperature and quality of the engine oil. The processing chip within the oil sensor collects the information from these three inputs and processes it into a 0-5 volt square wave signal that it sends to the PCM over a dedicated circuit.
The PCM is located in the control module box. The PCM receives inputs from the oil sensor via a hardwired connection. It calculates the useful life of the engine oil based on the level, temperature and quality of the oil. This information is bussed over the Engine CAN C Bus to the IC.
Sensor Operation
The processing chip within the oil sensor receives a signal from a three-wire position sensor that uses a 5-volt reference and ground. The third (signal) wire is connected to the variable resistance wiper. As oil levels change the wiper is moved by a float and produces a signal that reflects the current oil level.
The processing chip within the oil sensor receives a signal from a Negative Temperature Coefficient (NTC) resister type temperature sensor. The sensor uses a 5-volt VREF and produces a volatage signal that is inversely proportional to the engine oil temperature.
The processing chip within the oil sensor receives a signal from an oil quality sensor. The oil quality sensor runs current through an oil sample and measures its voltage drop. Fresh oil is a good insulator and would produce a high voltage drop across two probes. As the oil wears out (viscosity thins out, becomes contaminated etc….) the oil becomes more of a conductor and voltage drop decreases.
Flexible Service System
A computer- and sensor- supported maintenance system called FSS allows for individual vehicle maintenance intervals up to 30,000 km (18,500 miles) and servicing at intervals between one and two years. It also notifies the driver if maintenance is needed sooner.
·FSS calculates and displays in the IC the distance remaining to the next regular maintenance service based on actual driving conditions and oil quality.
·The computer keeps a running track of driving conditions and calculates a load collective that correlates to wear and tear on the oil, using equivalency factors for hard driving, normal driving and light driving.
·The display shows the number of miles under present driving style until the service interval is reached.
·The computer also monitors oil and water temperature, RPM, vehicle speed, miles driven, load and oil added. It compares this data to a model that determines when it is time to change the oil.
·An engine oil level sensor measures the dynamic oil level during driving and also senses oil (thinning) dilution or high metal content. If specific limit values are reached, the driver is notified that an oil change is needed.
·The sensor is also able to receive the static oil level and notify the driver if it is too high or too low through the trip odometer in the IC.

 

But tell us how to use the FSS calculator, other than by poking it twice.

I've read somewhere that the IC readout might also show +/-DAYS (time) to change or overdue. How does one convert from miles to days, or is this a conversion that occurs within the PCM? What do the stealerships know that we don't?

 

there is still only 1 way I know of to know the quality of oil, and that is an oil analysis by a lab equipped to do so. This device can't do that. It has set parameters to quess how long you should go, but no real way to know what the quality of the oil is. You could put used oil in there, based on the vescosity of the used oil, this would be determined by the heat build up, I would assume, it would give you an approximate time to change your oil. But it is still used oil. Just change it at an interval you are confortable with, but I won't believe this sensor crap...sry...no real way to know for sure what the break down of the oil is...

 

Doc, I am 100% behind you. Although I find this part interesting and worth researching if curious...

But also not using the recommended oil viscosity could throw the whole system for a loop and be inaccurate from the get-go.

James

 

its a grt gimmick, but that is all it is. If you were to send out a sample to a lab, from one of your oil changes, the results will be broken down with elements you didn't even knew existed in oil. They will also give you a recommended interval for oil changes based on this analysis. I know James knows this being in the bus business...I have had recommendations on my car oil up to 25K, but I wouldn't use that interval. Common sense tells you this is just too long...in the end, good quality oil, and common sense, you can't go wrong

 

Having an oil analysis is the only real way to determine how long you should go with your oil changes. Expense becomes the issue here. I am confident we can go 5000 miles without a problem. Have your oil analyzed at 5K and check the results. Many labs will give you a read out of everything that is checked with results, then a summary is written of what needs to be checked or repaired/changed. If good at 5K, have it checked again at 7k. If good at 7K, have it checked at 9K, and so on. You will find out when a good average mileage will be once you are able to sort out the results.

We do an oil sample on every oil change in our diesel fleet. If we see a pattern develope, we change mileage/time accordingly to get the maximum, but safe, life out of our fluids and filters.

James

 

I believe that they have done that for you already.......using base models and equivalency factors in their calculations based on averages. Granted, it is not vehicle specific, per se, but I wouldn't go so far as to call it a gimmick. That have already done what you two are suggesting with oil analysis, and modeling them for different driving styles, etc.

 

Gimmick or not, common sense prevails, but his little car still does some pretty neat stuff. It recognizes your driving habits (see resetting throttle history), uses that knowledge to test oil potential drop in one of three steps - light, normal or hard driving - and then predicts when you should change the oil.

Gotta' give it some credit. It sure does try.

 

Agreed. Short of managing a fleet of them and doing individual oil analysis on each unit, you aren't going to get any better.

 

But doc, in your post #31 in Help, Oil Change, you said you'd trust nothing but milage? If I really cared, I'd have a head ache. Ouch.

 

Damn, we need a chat room for this.....

 

I will change mine every 4K...it makes me take a look at things each time I am under there, and stay on top of things....vescosity can break down for a number of reasons, sometimes from just setting a warehouse too long... not going to risk a hand built AMG motor with short changing its life blood, just like I wouldn't short change my big truck...we learn a lot having driving trucks for over 3 million miles, and police cars for over a million as well. No one treats an engine any harder than those 2 professions. Oil is the number 1 factor in engine failures....by oil analysis, a high copper reading could head off spinning a rod bearing ruining a crank, thus the engine...don't take your oil for granted...I like racing mine, so I keep a closer eye on it, but nothing wrong with being safe....FSS on mine is for looks...don't even use it...

 

Dwight, go take an aspirin, while I take a chill pill....LOL.....done with this ****.....see ya...

 

Doc, I go along with everything you just said.....but you are not the norm. For the average Crossfire owner, the FSS is the best thing going. To totally pass it off as folly is extreme.

 

This is not Fernandez it's one of his buddies from work

It may not be as accurate as an oil analysis but at the same time if you get enough engines together and do enough testing you can get a general "slope" I guess you could say of how the oil breaks down over time at a given engine speed, load, temperature, ect,ect. and be able to program your system based off that information.

My Saturn has an oil life monitor developed by GM. It doesn't use a sensor but uses various factors (engine speed, temperature, ect, ect) during the operation of the engine to determine proper change time. That system is based on using a Synthetic 5W-30 oil so if you use something not within the GM Spec 4718M (which is like 7 diffrent syn oils) there's no way to know if they system will tell you to change at the proper time.

A lot of engineering and work went into the system and I trust that the guys with engineering degrees know more about this subject than I do. I simply spin my own wrenches not design, engineer, build, and refine engines for mass produced automobiles.

I routinley go between 7 and 8 k miles on an oil change. I have a few oil samples sitting out waiting to go to Blackstone labs but still haven't gotten them out yet.

If you're interested you can go to this link
http://www.redlineforums.com/forums/...il-life-7.html
It's a link to a page on the discussion of the oil life system on the Saturn. The first post on that page is probalby the most informative. We don't use the exact same system but it gives you an idea of the amount of engineering that goes into these systems.

 

For those who read Playboy only for the pictures.....

 

Yea....what's all those words about?