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Getting ready to install used motor in my 99 996.  Like to get IMS upgraded while it's sitting on the stand and I'd like to know what the experience level with DOF has been and what no-fail mileage has been obtained.  Engineering of it looks very sound.  Opinions do vary.

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36 minutes ago, GEE said:

Getting ready to install used motor in my 99 996.  Like to get IMS upgraded while it's sitting on the stand and I'd like to know what the experience level with DOF has been and what no-fail mileage has been obtained.  Engineering of it looks very sound.  Opinions do vary.


Hate to let the wind out of your sails, but the engineering is not as sound as you might think.  The DOF draws oil from a cylinder head, which is well known to be both one of the hottest and dirtiest sources of oil.  Ask anyone that rebuilds Porsche cylinder heads about how difficult it is to clean out cylinder heads during a rebuild and you will understand better.  There have also been multiple reports of problems with both the VarioCam systems and lifter noise when pulling oil from the heads, both of which ceased when the oil line was plugged.  And, as all versions of the OEM  IMS bearing seals are know to leak oil into the shaft itself, there have been questions about what that does to the loads on the IMS bearing itself.  While some have had success with this design, there are a lot of unanswered long term questions that remain definitively unanswered.


If you want a very well designed and proven retrofit system, look at the IMS Solution.  It uses a solid bearing that gets its oil feed directly from the oil filter adaptor, which is obviously the cleanest source of oil, and one of the coolest.  The system also uses a plug in the shaft behind the bearing to permanently prevent oil intrusion into the shaft.  Both of these features are part of multiple patents, which is why no one else uses them.  The IMS Solution has no moving parts, and is also the only permanent fix for the IMS issue, and the only retrofit bearing that can even be moved from one engine to another if needed.  And yes, it costs a bit more, but this is definitely an area where "you gets what you paid for".



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I had DOF fitted three years ago (about 40k miles) and it’s been absolutely fine. I feel much more comfortable with this arrangement than with the ‘standard’ sealed bearing. I change my engine oil every 10000 miles and only use Millers CF Nano oil as recommended by Hartech in the UK (I had their cylinder stabilising rings fitted at my last rebiluild. 


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