In fact, this is hacking me off now, with the pedantry that popped up on a previous (multijet?) thread where someone kicked off about the engines having an oil degradation sensor based on something about a mini- even then the conclusion "minis have an oil degradation sensor" is demonstrably falliable.
The 500 engines do not measure oil condition directly- in the case of a multijet they merely measure parameters that might affect the oil (number of regens, failed regens etc.) and use an algorithm to flash up a condition warning. It might be something like "when 10 regens or 5 failed regens have been done, flash up "change oil"" (it's almost certainly more complicated than that, but it gets the idea across.
When the multijet has an oil change the COUNTER is reset (so the ecu allows another 10 regens or whatever before popping up the "change oil" message). Nothing to do with measuring the state of the oil directly.
I'm sure we've seen people have an oil change on their multijets without this counter being reset get a few miles down the road and then get a "change oil" message- if this mythical oil sensor existed on the 500 this wouldn't happen as the sensor would go "oh, fresh oil" without any need for a reset and hence the reset would not exist.
In the same way, we can imagine a similar thing happening in the twinair, where the valves are moved by the oil. Assume as the oil ages it gets thinner [note, I don't know whether it does or not- petrol dilution might make it thinner and in any case the parameters could work both ways], so [again, to very first order approximations] the uniair system has to pump more oil through to the valves to get the same rate of valve opening (how you would measure it I don't know, but it illustrates the point). The uniair CU stores this "pump more oil" as a value that might increase as the oil ages.
Then, when the oil is changed without the value being reset it uses the same "pump more oil" value with thicker oil, perhaps causing issues.
In "in before the pedants" mode, I don't even pretend to understand the details of how the uniair system works, this was just an illustration as to how the engine could monitor oil condition indirectly, without an oil condition sensor.
Again, if the twinair had this mythical oil degradation sensor [which I never mentioned] monitoring the oil condition directly, the oil state would never need resetting (so examiner/
multiecuscan wouldn't have an oil change procedure).
If I'm honest, I'm getting increasingly sick of seeing this sort of thing happening on here.
