arn, knowing what has been posted on this thread, I would think this was the scenario. Just a guess so you can take it for what it is worth, no need for a nasty remark.
It looks like you ride in some dusty conditions, probably fairly severe. Lots of dirt in that filter for such low mileage.
Assuming the conditions cause the accumulation of dirt (not sure what else could be the cause), the restriction imposed by the dirt would cause the crankcase ventilation system to back up enough to allow oil vapor to condense on the air filter.
This seems to me like to most possible rational explanation of what occurred based on the evidence present.
I have not looked at mine, but I would bet it's practically spotless. Another factor could be if you ride in rain a lot and the filter got saturated with water on several occasions or even regularly.
Another factor could be if you ride close enough to other vehicles that your filter got a lot of dirt on it due to the vehicles in front of you kicking it up off the road. You can tell a tailgaters car by the paint chips and windshield chips that are much more numerous than typical cars, as well as prematurely plugged air filters.
All or any of these assumptions could be true or not, only you know the answer to that.
Just on observation on my part, no need for the typical forum attacks, it wont change 45 years of experience and 30 years of working on vehicles.
regards
Badger
Thanks for taking out the time to analyse it
You might notice the nasty remarks are only for forum trolls who add no value, don't bother to analyse what the problem might possibly be but are quick to come up with mean minded smart ass comments (or are paid by somebody to be as obnoxious as possible to those who point out concerns with the bike, valid or otherwise).
I'll give an idea as to the running my bike has had. It's been fast highway running for almost 7-8000km, with cruise speeds of about 110kph where possibly, the rest being comparatively sedate city running. For those who have been to India the speeds may sound high, but they are definitely do able on the main highways, especially at night when the jaywalkers, cyclists, odd villager who's strayed onto the highway have retired for the night.
India is dusty, no doubt about that, but the highways are not excessively so except in the few areas where there is construction work in progress. The "dust" on this filter is what I expected to see in any case, having a CRF 230 derived bike which has a very similar paper element, it's the oil that's the surprise. The CRF engine also throws oil into the box via the breather but that is downstream of the filter. This year there has been very little riding in the rains, mainly on account of a back problem, so it's a little unlikely that the water could have got sucked into the element, especially given that the inlet is tucked away under the seat, and is not like a ram air intake, for example.
As regards riding close, yes, that's how it is in traffic here, but all of it is at low speeds in the city, not much crud being thrown up.
I might have been inclined to think more in terms of an assembly or bike specific issue, but for the fact that nobody AFAIK had taken the filter out (I prefer to hang around while the service is done)
and there was that other filter at the service centre with very similar oil stains on it, and it was also in for the 12000km service, having returned from a tour of North East India.
This (dirty) side of the filter is in any case the outside, where the breather should not be sending any oil at all, and the throttle body side does not have any oil on it (just a bit dusty, within normal limits). I guess the service centre might receive some reply from Honda, I'll communicate with them sometime next week