Which scenario would one wind up w/a dirtier oil filter?

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This scenario on a GDI engine,all other things being the same and having 15k filter and using full syn oil.

Scenario 1: Changing the oil/filter 1x in 15k miles---no makeup oil

Scenario 2: Changing only the oil every 5k miles 3x
 
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There might not be significant difference, under favorable conditions.

I'd bet on Scenario 1, by a small margin---a wider margin if 15k is too far for the oil, engine, and conditions of use.

Possibly Scenario 2 if you believe new oil contains a lot of "dirt," or if you allow dirt to enter the fill opening during changes.
 
Originally Posted by CR94
There might not be significant difference, under favorable conditions.

I'd bet on Scenario 1, by a small margin---a wider margin if 15k is too far for the oil, engine, and conditions of use.

Possibly Scenario 2 if you believe new oil contains a lot of "dirt," or if you allow dirt to enter the fill opening during changes.

+1
 
In theory, there should be no difference ...

The oil filter has no ability to change the rate of contamination generated by the engine. Let's make up some numbers for an example. Perhaps the engine generates 1 gram of soot per 1k miles of use. (it's just an arbitrary number I picked; don't get too excited). In each scenario, the engine would generate 15 grams of contamination. How often you change the oil does not change the rate at which the engine produces the soot and insolubles. The filter, itself, is still exposed to 15k miles in both situations; hence it should be loaded about the same.

Again - more theory ... Soot loading does not change, but soot amalgamation will increase a bit. How much? Who knows? Soot starts out about 4 nm (nano-meters) in size, give or take a bit. That's 100x SMALLER than where even a bypass filter has good efficiency. The anti-agglomerates in the lube should be doing their job, and so it's hard to know how much the loading of soot will increase, specifically in the sizes that matter (sizes that the filter can actually trap). Generally, to experience decent efficiency, you'd have to be 5-10um in size. So a long OCI does not really assure that you're going to be loaded with huge soot particles. Never confuse the percent of soot present with the size of soot present; those are two entirely separate things. Also, PC analysis can help understand, but PCs do NOT tell us about composition; they only speak to size. There are insolubles that are not necessarily harmful that have size; don't forget that. Now, there will always be nuances that after this a tiny bit. But you're soooooooooo far off into the weeds here it really does not matter.


If you really want to know, then you'll have to run some experiements, and then get a lab to accurately measure the weight of trapped contamination. However, you'd have to run 30 samples of each situation, because without knowing the standard deviation, having only a few samples is pitifully too few to declare true knowledge.
 
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scenario 1.

Draining the oil will remove way more stuff even if your filter is not changed. Those acid that used up detergents, and those tiny particles that cannot be filtered out will be flushed 3x and not clump together into things that clog the filter.
 
Originally Posted by PandaBear
scenario 1.

Draining the oil will remove way more stuff even if your filter is not changed. Those acid that used up detergents, and those tiny particles that cannot be filtered out will be flushed 3x and not clump together into things that clog the filter.

What ????
Acids don't "clump together"; they are essentially soluble and would never be stopped by the filter anyway.
What "small particles" are you referring to? Metals don't amalgamate generally.
Soot will amalgamate, but as I said already, soot is misunderstood in how small it really is.
 
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I did not have a 15K filter but I have this new Miata with the factory filter. The Mazda info given was to keep the oil in for the first 10000 km (Aus. Owners Manual added the factory oil is good stuff, no touch...) I decided to change the factory filter at 2300 miles and try out my new filter cutter cause of curiosity. The pleats were clean except for some slivers of metal. (new engine) The oil was a shade less color than new.

Personally... what is the big deal about changing an oil filter when you do a oil change? Money? or do you believe the after market claim of 15000 miles. Changing the filter can only help and since you are under the car why not...
 
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