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Oil Life Systems

Change Motor Oil


New cars made over the last few years may have smarter, more sophisticated systems in place to accurately determine when your next oil change is supposed to take place.

This web page explains how they work and what they can and can not do.

What is Oil Life System ?

The only part of the "system" that a vehicle operator can see is either "indicator" or "Oil Life Percent" on a multi functional display.

Motor Oil Life

The "indicator" may be dedicated to oil change, or it is a "general" maintenance indicator.

Motor Oil Life

Currently there is not any universal and agreed on by all vehicle manufacturers way or method how to indicate "need for oil change".
Therefore you need to consult your owner's manual to find out if your vehicle has such a system, what it indicates and how.

In general, these systems look at driving speeds, cold starts, short-distance trips, and other factors that can negatively affect oil life. Based on driving conditions, the mileage at which an oil change is indicated can vary considerably.

What can Oil Life System Do ?

It reminds you that you should change your Motor Oil, and that is all it does, nothing more, nothing less !

What Oil Life System can NOT Do ?

How Oil Life System Works

Today all modern vehicles have multitude of computers, some of which are dedicated to just few functions and thus are "idle" most of the time.

Utilizing such on board computer for additional function, is just matter of mostly software, and perhaps few inputs and one output.

The OUTPUT is the signal to the "Oil Life indicator" no matter if it is a lighted tell-tale or alphanumeric display.

The INPUTs are digital or analog signals that are ALREADY collected by same or other vehicle computer for engine management, and thus no "special" sender that would send a specific "Change Oil" signal exists on the engine.

The "Heart" of the System is the ALGORYTHM, a software that monitors such INPUT signals as:

The ALGORYTHM is developed during vehicle testing and verification before the specific vehicle is approved for volume production.

Algorythm Graphic
Graphical Representation of Oil Life Algorithm

The ALGORYTHM is however dependent on the actual Motor Oil that has been used in the vehicle, which usually is Motor Oil that will be specified for "Original Factory Fill".

Since the ALGORYTHM or the computer INPUTS do not tell the computer what actual Quality the Motor Oil that is eventually used for Oil Change is, the Oil Life Monitor is therefore only "accurate" if the EXACTLY SAME as the "Factory Fill" Motor Oil is used.

That however, is actually extremely rare in real life, as there are hundreds of brands, and as many Motor Oil formulas, and each will in real life use "age" differently.

To avoid serious Engine problems caused by Motor Oil that has been in service far much longer than is "safe", the ALGORYTHM includes a "fudge factor" that is some "cushion" percentage, so that if the Motor Oil is not changed immediately when the "indicator" advises the vehicle operator, a serious engine damage would be "unlikely".

So realistically the Oil Life System is nothing more than a reminder to change Motor Oil, whenever the computer decides it is probably a good time to do so.

Most vehicle Owner Manuals also advise that the Motor Oil should be changed after certain interval (be it 6 months or a year), even if the Oil Life System does NOT indicate the need for Oil Change !

Some Owner Manuals also advice that the Motor Oil should be changed more frequently if the vehicle is NOT operated under NORMAL conditions.


The Oil Life Monitor System is only a reminder to indicate that Motor Oil Change is due.
It does not actually monitor the Motor Oil condition, but through use of Algorithm, a computer determines when Motor Oil change should be preformed, based on Inputs it receives from engine operating conditions, such as temperature, engine speed, etc.

The system is only accurate, if exactly same Motor Oil as was used for calibration, is actually used.

What to do when SynLube™ is used

When you use SynLube™ Lube-4-Life® in vehicle with Oil Life System, just re-set the Oil Life System when the Oil Life indicator is 10% or less or when the tell-tale (if so equipped) lights up.

A good practice is to check the Motor Oil Level on your Dipstick BEFORE you re-set the System, and use ADD Oil if Motor Oil needs to be replenished.

At each third re-set, the MicroGlass™ Oil Filter should be changed.

If the vehicle uses a "cartridge" Oil Filter, or if a conventional Cellulose media Oil Filter is used, then change the Oil Filter at every re-set.

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Last modified: 2013-04-25

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