Simply put, can these systems really work and do they make sense? Doesn't the oil still get contaminated with acids, doesn't it shear, what about water contamination? I've seen the claims and testimonials, however, I remain skeptical. The manufacturers say additives are replenished with "make up" oil, the oil that's added at each filter change. Just seems too good to be true.

Yes they work very well and the main reason for this is:

-Most bypassfilters work with depth-filter principle it means that the oil is forced to go through at thick filter medium (20-100 mm) instead of only 0.2 – 0.8 mm.
Therefore they are able to catch particles down to less than 1 µm and hold them.
-Research from GM and several other has shown that particles in the 1-10 µm range is the most damaging particles in a Diesel engine and most other oil-lubricated systems.
Particles of this size is going strait trough most spin-on filters.
-Even the best oil in the word gets contaminated, so if you don’t have a system to really clean the oil, you will end up with limited oil life.
-Water is another factor that limits oil life, so the best thing to do with a Diesel or Gas engine is to make sure operating temperature are correct and long enough to evaporate water from the oil.
- Since you remove particles that speed up your oxidation process in the oil, the additive package will keep a lot longer.
-etc etc

Volvo trucks have started to install bypass filtration on their new engines.
PS don’t listen too much at the ones that make their living from oil or machine spare-parts sale.

Lots of good info on this subject at NORIA.

Hope this helps
Regards Larse

It might help if we knew what type of oil and the type of industry you were talking about. Industrial hydraulic systems, engine oils, etc...

Thanks for the detailed response. Everything you've said matches what I've been hearing and reading for years, however, I remain skeptical. A bypass filter can't remove acid and it can't correct viscosity that has been changed as a result of shearing or other contamination, right? In my business, recreational boat building and repair, there are several manufacturers of these systems selling products that make incredible claims for extended drain intervals. The engines we use are all diesel, mostly in the 100 to 1000 hp range and used between 100 and 500 hours per year. For storage purposes, we stress storing a boat, for the winter for instance, with clean oil in the engine. So, this negates one of the advantages of a bypass filtration system. But does it matter, couldn't you use one of these systems just to have cleaner oil without extending your drain interval?

Is there more information on these systems on the Noria site? If so I didn't see it.

Thanks

More info.

http://www.practicingoilanalysis.com/article_detail.asp...edbookgroup=PowerGen

http://www.practicingoilanalysis.com/article_detail.asp...edbookgroup=PowerGen

http://www.practicingoilanalysis.com/article_detail.asp...rticle+Contamination

http://www.practicingoilanalysis.com/article_detail.asp...bookgroup=Hydraulics

All bypass filters are not created equaly. One system may claim to work and another actually does. Good research is a must when deciding on these type of products. Start by looking for a 1 micron filter and one that can remove 100% of water. A filter that can keep TBN strong in oil and all other parts of the condtion of the oil is a good one. We've been getting great results with diesel engines using oil analysis and this type of filtration of over 100,000 miles per oil change on our trucks. Our highway trucks have better results than the rest. TBN levels depend on the brand of oil you buy, anywhere from 7-13. The higher TBN the longer you can go. Cat oil, Superflo, and Rotella T have some of the highest TBN's.