Quote:
Originally Posted by Mark
Oil is intended to both lube and cleanse. Synthetics may hold up for 10,000 miles, but essentually dirty and/or contaminated oil is being run in a motor for that much longer of a time. Is it logical to believe that everything that has gone into an engine in 10,000 miles is/was contaminiate free?
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That mostly depends upon the quality of your oil filtration.
As long as the oil itself can hold up that long (and good quality synthetics can), than the real limitation is the quality of your FILTERS. There is a HUGE difference between say a conventional filter that maybe filters down to 35 microns or so, and something like the Amsoil EAO filters (that can filter down to 10 microns or less, and have much more capacity to hold junk before they fill up).
And for even better filtration (than you can get even with the EAO filters), you can go with "Bypass Filters" (a separately plumbed in micro-filter added to the car). A good "Bypass Filter" can easily filter down to 2 microns or less, getting virtually all of the harmful dirt out of the oil (any soot small enough to be missed by a good bypass filter, is too small to cause much harm anyway).
So with a good bypass system, dirt in the oil is essentially not a problem, no matter how long you run your oil (as long as you change your bypass filters when they fill up with dirt). And with the dirt in the oil problem solved, you then are limited by the much longer mileage interval until the oil itself breaks down. And even with mid-range synthetics, that can easily be over 10,000 miles (and with premium synthetics, it can be 20,000 miles or more).
BTW:
I use both the premium Amsoil EAO filters, and a seperate bypass filter system in mine and my wife's cars. So for both our cars, the oil filtration is top notch (essentially making "dirt in the oil" a non-problem for me). And I also use top rated synthetic lubricants that take a very long time to break down. As a result, I've already got 10,000+ miles on my current oil change, and I still haven't decided when I'm next going to change the oil (likely before next winter, but I may decide not to do it before then), as the oil still seems to be in very good shape. Instead, I simply add a little "make up oil" every couple of thousand miles or so, just to keep the oil sump (dip stick) topped off...
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