Hi Jeffery,
to the contary I strongly believe in by-pass oil filters - but only the centrifuge type
See under "Centrifuge By-pass filters" on here
I use the MANN-HUMMEL centrifuge type (at $A1800 each)in my heavy 500hp trucks and I can state that without them the extended drain intervals I run - 100kkms - would be impossible. We gather contaminants at a rate of about 0.0025g/km with these filters and they effectively make the full flow filters redundant. Much of the contaminant load is soot, but not all of it. They are cost effective for me and I am now running one vehicle with stainless steel 30micron FF filters again to see if flow/pressure changes occur
I will shortly post again in the Diesel UOA's section and it will detail the effects of a non operating centrifuge and its effect on the OCI
The trucking and earth moving industries were "brought up" on the old style cartridge type by-pass filters. They were almost a requirement in the 1950's and into the 1970's and they also acted as an oil cooler by being placed in the air flow and holding about 20 litres
Regardless of what is said here on this Forum "toilet roll" by-pass filters have never been seriously considered by fleet users - the centrifuge is simply a better and more efficient device
They are used as OE in trucks and marine diesels and many other sophisticated applications
I have extensive knowledge of the lubrication and cooling systems of Porsche V8 engines. They are simply an excellent and conservative design with a large over capacity - both in a technical and practical sense. The secret being the large capacity cooling system and sump, the thermo oil cooler and the alloy structure of the engine
Porsche here where many Cayennes have been sold absolutely frown on add-on lubrication devices such as by-pass filtration. We get road surface temps here well over the 90C mark and ambient temps in the 50C region
One reason to be circumspect about fitting a centrifuge is that they actually take flow from the system and sometimes the pressure/flow reduction may have a counter productive effect. On my trucks the reduction is about .5bar which is acceptable to both Detroit and I. These engines are now at about 1m kms without a problem in that regard. The oil temps in these vehicles average about 103C and reach highs of about 113C - shutdown warning commences at about 118C with auto shutdown occuring at 120C
Many Porsche V8 engines have already covered 500k (miles) on either mineral or synthetic oils without rebuild
Kind regards
Doug
[ March 06, 2004, 07:47 PM: Message edited by: Doug Hillary ]
