So do these things actually have sensors that measure the amount of dirt or whatever in the oil to calculate % of oil life left? If so, what all is invloved/what are they measuring?
Or, is it as I suspect and they just count x thousand miles since last oil change?
I actually asked my service tech that the last time I had my Jeep in for an oil change.
He told me that while it doesn’t test the oil directly that it does monitor the things that affect the oil. Temperature, RPM, distance and probably several dozen other factors and then calculates an estimated degradation.
He also advised me to wait until the oil service light comes on before scheduling a change. That’s been between 5 and 7 thousand miles for me so far.
Interesting. Thanks!
I was coming back for an ETA after some Google, and most articles concur.
Interesting article, despite the obvious shilling of their Top Tier AMSOIL Signature Series Synthetic Motor Oil.
So next question: why is idling considered bad for oil life? Is it because no miles are put on it, thus reducing the average? Or is there something else? Because to me it seems the idling eould be the absolute easiest on oil other than having the engine completely off.
Synthetic oil and advanced filtration can extend oil life almost indefinitely. A standard full-flow oil filter will filter down to 20 microns, this will protect your engine for around 20000miles,
if you add an oil bypass system that filters down to 1 or 2 microns you can in theory run the same oil forever, you still need to change the bypass filter every 20,000miles or so & this has to be used in conjunction with a good oil analysis lab to make sure the contaminants are being caught by the finer filtration & that the additives haven’t been depleted. This is common on trucks over here and 80ks between oil changes is considered conservative.
I don’t think this is true. Even if a filter could remove particulates down to 0.0001 micron in a single pass, you still have to contend with the oil being contaminated by gasoline over time.
Immediately after a cold-start, low temps cause problems:
During normal at-temp operation, injected fuel evaporates and mixes relatively completely, forming a stoichiometric mixture that consumes pretty much all the fuel and air when ignited. At low temps, the fuel can’t completely evaporate in time (just the lighter-weight components), and in fact can’t even evaporate enough to form a combustible mixture. The computer knows this, and when the engine is cold it injects extra fuel, providing enough of the lighter-weight components to evaporate and form a combustible mix. This means the heavier fractions of the fuel don’t get evaporated or combusted - they slather onto the cylinder walls, diluting the oil that lubricates the piston rings and piston skirts and drooling down into the sump, diluting the oil there.
One of the combustion products is water vapor. When the engine is cold, the water in the blow-by that leaks past the piston rings and down into the sump condenses out, depositing water into the crankcase (and there’s more blow-by in a cold engine than in a hot one, because of ill-fitting pistons and piston rings).
Other reaction products from incomplete combustion also end up in the cold crankcase oil.
Idling doesn’t warm an engine up very quickly. It’s the least amount of power an engine can possibly make, i.e. just enough to keep the machinery spinning, and that dumps very little heat into the combustion chamber walls. If you increase the load on the engine (e.g. by putting it in gear and heading down the road), you dump more heat into the cylinder walls, heating the engine up to normal operating temp sooner. With parts and oil up to temp, you’ll be dumping less combustion-related contaminants in the oil, and the oil will last longer. This is why car owner manuals often advise different oil change schedules depending on how you drive: if you do a lot of short trips, you’ll have more cold-starts per 1000 miles, and the manual will advise more frequent oil changes.
If you go on a long enough drive that gets the oil up to operating temp and keeps it there long enough, you’ll drive off all of the water and fuel that was put there by cold-starts. But the chemistry of the oil definitely does change over time, even with particulates being removed.
I was told once that heavy-duty truck engines can be designed to burn oil so that aged oil is steadily consumed and the addition of new make-up oil from time to time brings in the various additives and stabilizers at a rate sufficient to keep the crankcase oil properties within a healthy range. If true, this would eliminate the downtime associated with oil changes; you’d just need to swap out the filter(s) every now and then.
In my personal experience, modern truck engines rarely need oil top-ups. They are built to exact tolerances and unless they are abused, a million kilometres is not considered exceptional.
Railroad crankcases hold about 300 gallons of lubricating oil and it is not changed between engine rebuilds at about 100,000 miles. At the end of each run sample is drawn and analyzed to make sure there’s no bearing metal particles or other contaminants that shouldn’t be there.