[Sirrotica]

Originally Posted by HWYSTR455

Only issue I see with extended interval oil changes is contamination from 'liquid' contaminants, or the breakdown/effectiveness of additives in the oil. No filter regardless of how small a particle it traps is going to filter or correct those conditions. The oil can look perfectly 'clean', and still suffer from those conditions. .

From Blackstone labs about the much better efficiency of by pass filtering over full flow inline filtering. Also addressing the topic of extended oil changes and peoples phobia about not getting "bad" oil out of their engines. Bad oil is dirty oil that regular oil filters cannot keep clean because of their design, it is still plenty capable of lubricating, but the contaminants that are left in it are also causing wear on critical surfaces in the engine as they re-circulate:

We receive many oil samples from clients who don't understand what is required to run unusually long oil use intervals in their engines. The accumulation of wear metals, blow-by materials, and oil oxidation products in their oils is alarming. It has been our experience that one cannot simply add oil of a particular brand or base stock and expect it will be useful for an extended period of time, lubricating, cleaning, and cooling as required. Oil that becomes contaminated needs to be changed promptly. In our opinion, there are no magic oils or additives.

There are, however, auxiliary systems you can add to your engine's lubricating system that will keep the oil clean enough to use over an extended period of time. By-pass filtration units are the most common system used for this purpose.
In-line oil filtration, which comes installed on your engine from the factory, filters oil entering the engine down to roughly 30-40 microns (millionths of a meter). This is about as finely as in-line filtration can filter, because when the oil is cold or the filter is partially plugged, a finer filter would cause too great a pressure drop, forcing open the filter by-pass valve and allowing unfiltered oil to circulate through the engine.

By-pass filtration works differently. When this type of auxiliary system is installed, some of the sump oil by-passes the in-line filter system, passing continually though a by-pass filter and then returning to the oil sump. Using this method, sump oil is constantly being cleaned any time the engine is running, and it can be filtered down to a very fine size. All you have to do to maintain the system is occasionally change the by-pass filter.

Not only do the by-pass filtration units cleanse the sump oil of blow-by and oxidation products, they also reduce wear metals and silicon accumulations, both of which are abrasive. Oil does not wear out. Its usefulness is limited by contamination. By-pass filtration removes most of the contaminants.

How long can an oil fill be run using by-pass filtration? We've heard claims of large (Class 8) diesels going 1,000,000 miles on the same fill of oil with no harm done to the engines. We have analyzed oils which have been in service 240,000 miles and found nothing unusual in the analysis, other than higher than average iron and lead (from steel parts and bearings), and these wear accumulations were not intolerably high.

After having run many tens of thousands of diesel engine oil samples, it is our opinion that a by-pass oil filtration system is one of the most important factors in extending oil drains. If you are interested in extended oil drains, we suggest you investigate adding this type of system to your engine.

One other thing that hasn't been addressed much is the total efficiency of a filter. It may filter to 40 microns but if it's 90% efficient 10% of the particulate is still getting through. Ideally filters in the 98-99% efficiency area are about the best out there.

As suggested by the article by Blackstone, if your only using a full flow filter your throwing your oil away very prematurely simply because of the design of the inline filter limitations it cannot keep it clean.

My own test with my 6.5 TD of 25,000 miles with regular Shell 15W-40 Rotella and 4 + years on the oil has proven to me that it does not just appear clean, it actually is clean, and able to safely carry out all the duties fresh oil is capable of.

What all comes down to, is no matter whose name is on the side of a full flow can, the design is very inefficient. There is no magic can filter that is anywhere near as efficient at keeping oil clean solely because of the design limitations. Filtering oil down to even 20 microns (Very unusual in a full flow filter) is still leaving a bunch of damaging/wear causing particulate re-circulating through your engine. As has been cited the 5-10 micron contaminants cause the majority of wear. No can filter even addresses those. The industry says at 5-6,000 miles, or sooner under extreme conditions, you need to throw the contaminated oil away because the small abrasive bits are getting more dense because the can filter has no way of removing them. The more concentrated they become the more they are wearing engine parts.

Now if you have a by pass filtration system from day one they are getting removed from your oil. Not recirculating and causing wear, not depleting oil additives, they are not building up because they are getting filtered out on the first pass through the by pass filter. It's black and white, apples to oranges, there is no comparison to a compromised design full flow filter and a dedicated 100% by pass filter. From the get go, they are different animals, one is a compromised design that must under all circumstances must keep oil at the internally lubed parts, while the other is a dedicated design that has only one duty. It has to clean the oil 100% to a very high standard slowly (compared to a full flow design) and return it to the sump. No condition that it must meet to keep lube to the internal parts no matter if it's clean or bypassed totally by the filter, no bypass valve.