TD5 - is it normal to have oily residue in post air filter pipe?

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Originally Posted by Blknight.aus

the one I just put in to replace Markndebs dirt collector was a deefer item the filterboxes look identical as far as I can see and the filter fit perfectly....

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Any idea why theres two different codings?

different manufacture supplying them? might account for the 2 different colours Ive seen on mine when it was getting serviced by the stealers.