Quote:
Originally Posted by Frozenr6
Sorry I know that I am a noob, but there are some serious myths here about oil and lubrication. As an example I have run regular dino oil in engines tha run at 85% duty cycle all day and night for the equivqlent of 40,000Km's. The reason to change oil every 4-5000 miles is that from a cost benefit perspective it is cheaper than taking regular samples to extend the interval.
Using a high quality filter we all under normal conditions could likely run the oil itself 10's of thousands of mile by only changing the filter, but that would require detailed understanding of the oil properties at any given time, hence cheaper just to chnage the oil.
Sustained viscosity breakdown is typically not caused by heat, that is genrally isolated to the event, but rather it is caused by an external contaminant be it coolant, moisture or by-products of combustion leaking past the rings(normal).
The most significant reason to have your vehicle serviced is to have the filter changed, at all costs the filter must not be allowed to become sufficiently plugged as to go into by-pass. The damage done with no filtration is near instant and is certainly irreversable.
When do you want to change your oil is upto you, synthetic oil changes should not be significantly longer than dino oils, because at the end of the day they have a finite capacity to carry contaminants and I have not seen a study that says they are measurable different.
I could probably ramble all day but will stop there.
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You are more well versed in this subject than most in this forum.
Our navy ships have a centrifuge for filtering the oil. If I remember correctly (since retired), the oil is filtered down to pass particles less than 5 microns. The oil is not changed because of the excellent filtration from the centrifuges. Plus, it's just not practical to change the oil when at sea. Oil Temperatures are monitored using thermocouples at all journal bearings. So, like you correctly stated, if you can filter the oil down to an acceptable level, e.g. 5 microns, there is really no need to ever change it. Oil pumped into the journal bearings provides hydrodynamic lubrication resulting in no metal to metal contact between the rotating journal and the babbitt material of the bearing. The greatest bearing wear occurs at startup when there is little lubrication and the oil temperature is at ambient let alone hot! And when the oil is being pumped through the journal bearings, any small particles from engine wear normally pass right through and get filtered or the small particles will embed in the babbitt material which is designed to have a softer material than the hardened journal. In either case, it is expected that no damage will result. Now when components get bent or go out of round, it's not the fault of the oil but rather exceeding the parameters of the engine design e.g. subjecting the engine to excessive loading outside of the engines design parameters.
Someone asked what this had to do with the Z? The principles are the same only on a much, much smaller scale. The oil is filtered down to 30 microns I believe. Still small enough to pass through the journal clearance or embed in the bearing. Exceed the 3.7L engine parameters e.g. overloading and your looking for abnormal wear and hence, premature failure. Keeping your oil clean is more important than oil temperatures running for example a steady 220F and intermittent temperatures in excess of 260F. I'm not the least bit worried with the lub oil system on my Z. Tracking though takes on a whole new meaning.
Oh, almost forget. Stormcrow, the Canadians were in Afghanistan long before the US showed up. So I guess it's the US aiding Canada. Admittedly, you have the bigger guns.