Hard working vehicles in hot dusty conditions demand the best oil and filter.


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Better Filters make Better Oil

Over the many years I have been involved with 4x4 Australia magazine, I have tested a lot of different oil filters and used many different sorts of oils. The results have been backed up by the use of scientific oil analysis.

Today more than ever, there are more sophisticated oils and better filters on the market than ever before and there is no doubt you can get a longer life out of your engine oils, if you have a better filter. Here's one we recently tested.

Now you gotta remember or be aware of the fact that for all intent and purposes oil does not wear out, breakdown or deteriorate. Sure, during use it becomes contaminated with water, acids, carbon, dirt, metal particles and sludge, but it doesn't wear out. So in theory if you have a perfect oil filter you would never have to change your engine oil.

That's the holy grail I've been seeking!


red line oil

Over the last few years I've been running Red Line Oil which is a pretty fancy, fully synthetic oil that has seen me extend my oil changes out to as much as 100,000km – see:

That oil test was done with the backing and knowledge of scientific oil analysis testing we carried out every 10 to 20,000km and the addition of a very low tech 'toilet roll' bypass filter. Those bypass filters are a pain to change and clog up relatively quickly so you need to change them regularly. Then the bypass filter, which I've had for around 100K, started to leak and I needed to find a replacement.

Since changing the oil at the 100K mark, I've run the Patrol out to 30,000km at a time, changing the oil filters, topping up with Red Line oil and taking an oil sample, as detailed later in this article.


micfil filter









Complete MicFil filter kit.

Then at the beginning of 2013, I heard of the new MicFil oil filter, which is designed and manufactured in Germany and can be used in oil, hydraulic oil and in fuel systems.

The ultra fine filter insert is the key to this filter and consists of a tear resistant fibre mesh with cellulose fibres of the highest quality woven through it. It looks a little like a fancy toilet roll but there's where the similarity ends. These filters are rated to 0.5mm (0.5microns), have a very high contamination absorption capacity, a long life span, low differential pressure and are water absorbent.

micfil filter







An ultra fine element is key to a filter's performance.


oil filter

The filters are available in three sizes, the smallest (the FE150) being suitable for engines having an oil capacity of up to 50 litres. This particular unit measures 175mm high by 130mm in diameter and is made from heavy-duty cast aluminum (there are stainless steel cases available as well) with all working faces machined to a near-mirror finish. The sturdy lid is sealed by an O-ring and held in place by four good size S/S bolts. It's easy an away the best and most robust bypass filter housing unit I've seen. And while changing oil filters, especially on a diesel engine, can be a messy job, this unit has made the job as good as it gets.   

Unit is well made, robust and easy to access.








Hoses must be secure to prevent leaking.

The replacement interval of these filters is 500-600 hours and, I'd hazard a guess and say that since my Patrol only takes around 11-12 litres of oil even with the additional MicFil filter, I'd be looking at the 600 hour mark. That's probably somewhere around 40,000km before a filter change!










Fitted assy in Patrol.


Testing in Germany with big truck engines and the like, using regular oil analyses, has indicated that with a MicFil bypass oil filter, oil change intervals can be extended out to 20,000 hours or more. That's something like 1.3 million kilometres! In fact, Micfil, state a couple of times in there pamphlets that, 'no oil change is necessary after the installation of the Micfil ultra fine oil filter'. I'm not too sure about that, but it sounds promising!

When used as an oil filter the MicFil is to be fitted as a bypass filter (ie. in parallel to your main oil filters) and I had the crew at Outback 4WD in Bayswater set the system up for us, with the fairly large FE150 filter assembly, being mounted on the firewall.

On our recent trip around Oz where we clocked up 31,000km, saw me change my normal engine oil filters at 15,000km, leaving the Micfil filter alone and topping up with just 2.0 litres of Red Line. 

Back in Bayswater we took an oil sample and sent it off for analysis to see how it fared (see Test 2). The oil analysis report we get back is very comprehensive with 22 minerals listed, along with soot, water, viscosity, oxidation, fuel dilution and much more included.     

Test 1 was after 27,000km (in the USA) after one oil filter change and with the addition of 3.5-litres of oil to replace oil lost during that filter swap. The MicFil was not fitted at this point in time, but a dunny roll type filter was (ie a Frantz type by-pass oil filter).

The sulphur level has increased slightly in Test 2 (with the MicFil) and that is mainly due to the increased distance travelled (25% more) between tests 1 and 2.

Pentane Insolubles (PI - is a measure of soot of a certain size) and TGA soot  (which is a finer form of soot) are both improved with the MicFil, even though we've done some 6K ... or 25% more kilometres. In the past we've had PI readings of over 30 and TGA soot figures of six (due to poor engine tuning and running at high altitudes in South America) so we are a long way short of that.

The table shows a slightly less figure for TBN with the MicFil filter, but this is most likely due again to the higher kilometre figure than anything else. For those that would like to know, TBN stands for ‘total base number’ and refers to the reserve alkalinity the oil has which fights the acid formed in the engine. This acid formation in the engine comes from combustion, high temperatures, exposure to oxygen, sulphur, fuel dilution, along with water from the combustion process or condensation. If this reading was below one or two you'd be thinking of changing the oil.

Helping that TBN figure is the improvement in the amount of water in the oil, even though on our trip through the Pilbara, Kimberley and Cape York we crossed a lot of flowing creeks and rivers, which adds water (via condensation) to the oil. With the MicFil the amount of water in the oil is some 100 times less than with the previous oil filter system. 


red line oil test

As far as viscosity is concerned Red Line starts at 14.5 and can go up to as high as 50% more than the original, meaning it can increase to over 21 before there is an issue. Again the MicFil is better and at 16.24 the viscosity of the oil has only shifted a small amount from new.

One other thing that should be noted is the iron reading, which is probably the biggest indicator of wear in an engine like the TD42. Over the course of all our testing with Red Line oil, the iron figure has remained remarkably stable at around 55-65ppm for 25-30,000km, some five times better than a good quality mineral oil we tested previously. 


































This latest oil analysis came back with two other comments.

'Fuel dilution is low and the amount of water is excellent.'
'Silicon and aluminum was slightly higher than normal, but is not of concern, however it does suggest a slight dust intake.'

That was probably due to the dusty conditions we were in much of the time and the fact that I let the air cleaner element get dirtier than it should have before I changed it. When you do an oil analysis, believe me, there is nowhere to hide – any wrong doing or change, such as the use of an injector cleaner, etc, will all be picked up!  

So, I'm more than happy with the improvement the MicFil has had in oil quality, the improvement in the interval of filter changes and the ease of changing filters.

So you are saying, what's the cost?

The oil filter assembly which comes complete with hoses and an element along with fitting instructions is $1275 for the FE 150 model which is suitable for all 4WD vehicles we use. Spare FE150 filter elements cost $135.

That may sound expensive but the savings in oil and filter changes is reasonable (see below) with standard costs for a 4.2 Patrol being around $630 for oil & filter changes over 30,000km. In comparison the costs in oil and filters is $435 over 30,000km with the Micfil and the Red Line oil.  

And then there is the convenience. I mightn't have reached the holy grail yet, but I've got a lot closer. And not changing oil while on the road travelling is, I gotta tell ya, a real god send.



Normal Oil
(10 litres)

Normal Filter x 2

Red Line Oil
(10 litres)

With MicFil Filter





2 filters - $30



2litres only -

2 OE Filters only - $30



2 filters - $30








2 filters - $30

10 litres - $200

2 OE filters - $30 plus
1 Micfil Filter







After sampling this last lot of oil I've changed the engine oil, once again filling with Red Line. Now I know what to expect, I'm going to continue to run the Patrol out to 30,000km, with just a change of the normal Patrol oil filters at the 15,000km mark. At the 30,000km mark I'll drop the oil and change all the filters. Sure I could go longer it seems, but I'm more than happy with that - it's as close to the holy grail as I can get at the moment!

Filter element after 30K was still in good physical condition.


Take Note .... a Word or two of warning!

Your engine and oil use may well be different to mine and the ol' Patrol.


Modern engines are dumping more and more contaminants into the oil, so the engine can comply with environmental standards, while the oil has to work harder and carry more crap.

Many modern engines also have longer oil change intervals and while, with a good aftermarket oil filter, you will be able to extend that oil change interval, without proper oil analysis you don't know when you must change it.

Also, other high grade oils may do just as well as the Red Line oils I've been using over 30,000km, but without oil analysis you again, ain't going to know when you need to change it.

Cooling an engine suddenly in a creek crossing can cause condensation to form in the oil - but you'd need to be deeper than this.


More Info

MicFil filters are available in Australia through ProQuip, in Bayswater, Vic. ph: (03) 9761 1110 or visit:

For technical info:

These filters are available Australia wide through good 4x4 stores, such as Outback 4WD in Bayswater, where fitting is available; ph: (03) 9720 6226;

Red Line Oil is made in the USA, but isn't readily available here in Australia. You can find it on the web, or at the Oil Store ( in Cheltenham, Vic, or at GL Lubricants ( in Regents Park, NSW.


See you in the bush.

Ron and Viv.

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