Air Filters

This is a blog from Chris Blakemore, normally I don’t filter his work (pardon the pun), but in this case I took a look and decided to add this pre-text. Yes Chris is a retailer, but more than that he believes in supplying quality products that work, that will last, that will protect your vehicle and ensure its longevity. As caravaners and 4WD enthusiasts we sometimes overlook, don’t understand or simply don’t care about what is under the hood … well Chris does!

G’day, Chris here again, still clearing the dust from my nose.

I sometimes get a weird look from customers when they comment their Unifilter looks dirty and near clogged up and I reply “Great!!” Our recent trip across the Simpson Desert found a few filters thick with red dust. Ironically one of the better known diesel experts in the country regard oiled filters as troublesome because they can choke up, but agree it is a service issue (owner) not a product issue.

An air filters job isn’t to let all that grime through into your engine, nor can it somehow magically dissolve it and pump it out the back. A good filters job is to grab as much as it can below the point of being unhealthy for your engine and hold it there until you next service it. Simple as that.

Of course every manufacturer of filters and especially vehicle manufacturers claim their filter is the best. So how do you sort the chaff from the hay, or filter out the crap per se. Well its not easy so here’s a few recommendations based on our experience, knowledge and a few facts.

Firstly, we choose Unifilter oiled foam filters for all our customers 4WDs, including brand new vehicles we service under warranty. Why? Because they perform best and help engines last longer.

OK, this is where Chris get’s a bit technical … read on it’s worth it and you might learn something!

You see, paper filters have a limitation called porosity. Essentially a paper element is porous enough to allow sufficient air through before your engine stops breathing. To do this it has miniscule holes and based on current technology and engine performance that means they can filter down at best to 12 microns in dust particle size. Pretty damn small. But given that particles above 15 micron can start to cause excessive wear internally its as close as they can go to being in-effective. Paper filtration by car manufacturers is still driven by price otherwise they would all use ‘performance’ filters. Unfortunately many manufacturers are very reluctant to disclose the real micron performance of their filters and instead refer people to the SAE J726 standard. This talks about ‘efficiency’ such as filtering 90% efficiency at 30 micron. OK, so if 10% got through at 30 micron size, what is getting through at 15 micron?? Importantly though, one should never attempt to ‘clean’ a paper filter by blowing out dust with compressed air as it may in fact damage the porous media and cause blockages or worse, blow them out open.

FILTER-1              FILTER-2

Another common filter brand uses cotton gauze as a filtration media, which flows exceptionally well and widely used in racing circles. This is fine except if you encounter dust upon which they recommend using oiled foam pre-filters to minimise dust ingress. Now given the likelihood of 4WDs and RVs encountering dusty roads in Australia its fair to say this cotton gauze option may not be the best in terms of engine longevity. A new set of rings in a twin turbo V8 diesel can lighten your wallet a bit.

So I come back to oiled foam filter media which filters down to 4 micron and 24% better flow than paper. Sort of makes sense doesn’t it. More air, less dust, better engine life and performance. Oiled filters are also serviceable, not a throw away paper element, so deliver great value too.

So next time you check your regular filter after a long dusty road and it looks no different from when you put it in, at least you’ll know where it all went….!

See you outback. Chris

Well there you go … Chris recommends Unifilter.

RView normally doesn’t endorse products or sell goods, but if we believe something is good we will review it (or as we like to say RView it) and anything that’ll ensure we’ll make that next trip (and back) safely and mechanically sound is something worth considering.

Yeah, see you outback Chris … Cheers, Andrew

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