OK. I have taken RR's advice and have been exchanging emails over the past few days with the technical manager at ITG.
I shall precis:
ITG apparently take 3-4 enquiries a month about oiled filters and MAF sensors. In seven or eight years they have apparently only seen one genuine case of one of their filters contaminating the MAF sensor, which was caused by the filter being massively over oiled.
But 'independent' opinions would NOT agree with ITG. Perhaps you out to also get the opinion/advice directly from say Bosch or Pierburg who manufacture the actual MAFs - they will categorically NOT support ITGs opinion. Or how about a third opinion, from Volkswagen Germany - and ask them if using any non-standard air filter, and particularly an oiled one, will have any effect on the MAF. Ask them if the MAF warranty will still be intact too!
They evidently take great care to ensure all excess oil is removed from the filter during manufacture. The foams are passed through what is essentially a mangle to squeeze out the excess oil, leaving only a light coating on the foam. Add to this the fact that the oil used is extremely thick and tacky (it actually has to be heated to get it to flow into the foam), there is very little chance any of the oil on the filter can become airborne.
The reason there is oil in the bottom of the bag when the customer recieves the filter is because it will slowly seep and spread itself; if the filter had been packed and sat on a shelf for a few weeks, gravity will have caused some of the oil to slowly seep out and pool in the bag.
So on the one hand, they are telling you they need to 'heat' it up in order for it to flow INTO the foam - yet stone cold British winters can cause it to then dribble out again. There is some serious BS in those two highly contradictory comments!
Although the thought of having oil spreading itself would indicate that oil could get onto the MAF, you need to consider the design of the airbox. In 99.9% of housings the MAF is mounted above the filter, so oil can only spread into the base of the box, not the lid.
OK - and what about when you are in a 50mph wind. Stand on a beach, or even next to a puddle, and be downstream of a wind - and you are certainly gonna get wet from the water being whipped up by the wind!
OH, and the Golf GTI, and all the other variants which use its engine (which happen to be part of the worlds third largest car maker) are in that 0.1% of engines - because the GTIs MAF and airbox are on the SAME LEVEL. More BS, me thinks!
The capillary action of the oil is also a key point in the way that oiled foam works.
And????? So it can flow by capillary action - yet had to be heated to get it applied in the first place. More contradictions!
The reason ITG have to use oil on the foam is because without it there is nothing for the dust and dirt to adhere to – dry foam filters will eventually let dust pass as the constant airflow and vibrations work the dust through.
Exactly. Which is why open-cell structures like foam are BAD as a filtration medium.
As the dust starts to build up on the oiled foam, the capillary action of the oil causes it to spread over the newly laid down dust and hold it in place – without this spreading of the oil, dry spots would form and allow the dust to tunnel its way through the foam.
What an utter UTTER load of bollox. Once the oil has absorbed a certain amount of dust and grit - that's it! It can NOT absorb any more. And NOR can it somehow 'create' more oil. That is a very serious, and blatantly misleading comment!
Although the oil will spread, it is too thick and tacky to actually get pulled away from the filter as air passes through.
Hmmmmm - so it is too 'thick and tacky' NOT to get pulled off the filter by a 50mph wind in the inlet tract - yet in a ZERO windspeed, it can freely run out and pool in the bag or airbox - there must be a truely massive field of bovine deficant!
This is, however, something that can apparently happen with the lighter oils that are often used on cotton gauze filters. Foam filter oil needs to be sticky so it can adhere to the foam, with cotton gauze filters the oil is intended to soak into the cotton. This means that if the filter is over oiled, it is quite likely droplets of oil will be picked up by the air as it passes through the filter.
'Air filter oil' is air filter oil. Grades are NOT specific to cotton or foam or whatever. To state that it can run from a cotton filter, yet somehow magically can NOT run from ITGs foam - is again grossly misrepresenting FACTS.
After manufacture, the ITG filters are wrapped in paper towelling which helps wick out any excess oil that may have been left after passing through the mangle.
So it would seem an epic fail, if there is a massive pool of oil in the bag!
I don't have the technical knowledge to confirm the veracity or otherwise of the response from ITG, but I am extremely reassured by the trouble they have gone to to answer my questions on this subject. Others will no doubt make up their own minds.
Reassured - sure you arn't being a little guillible?
And 'trouble' to answer your questions - FFS, that is the FIRST thing they should be able to do!!!!
