Hi Folks,

Does anyone have experience of the Scotts stainless steel oil filter on the Tenere. It makes sense for me as I head north into the Yamaha Servicing Hinterland I don't want to fill my panniers with filters), and whilst I'm in Santiago for a few weeks I may be able to get hold of one.

Can't see any reasons I shouldn't use one if I can get one - but having no experience of them, I thought I'd ask.

Gratias, Amigos.

Paul

Personally I wouldn�t use a washable mesh oil filter on any motorcycle that has a common oil supply for the gearbox, clutch and engine. Mesh filters only filter down to 30-35 microns, whereas most paper type filters work down to 20 microns and some claim to filter out particles down to 10 microns. The abrasive particles that come from the clutch friction plates are typically around 20-30 microns and would not be removed by a steel mesh filter. Scotts calculate their filtering capacity over a three-way pass, which is a bit of a cheat (even though they say it�s a good thing), as filtering efficiency improves after initial priming and operation � in other words the more clogged up it gets the better it filters! The SAE agreed standard test is a one-way pass.

Mesh filters are absolutely fine used in the right application. My 1967 BSA 650 twin uses a steel mesh filter without issue, the engine has never been rebuilt. However, it carries a whole gallon of oil and that only serves to lubricate the engine, the gearbox has its own oil, as does the primary drive and clutch and the oil pump is designed to deal greater flow on a mesh filter. Older Japanese bikes used mesh too, but also carried a whole lot more oil than they do now. For example, early WR450s used brass mesh filters, but when Yamaha wanted to shed weight (and reduced oil capacity to achieve it) they changed to paper and the reason they quoted at the time was because it has a better filtration capacity.

Scotts state that their filters have a higher flow rate, that in itself sounds a good idea, but the flow rate needs to match the design of the rest of the lubrication system. An increase in oil filter flow rate over the OE design rate can cause low oil pressure � not ideal.

At almost ten times the price of an paper filter, I can�t see how they are going to save money. They aren�t going to save bike down time either, as they have to be changed (cleaned) more often and the washing process takes additional time in itself. Standard paper filters aren�t exactly a bulky item either, so I can't see why stashing a spare or two would be a problem?

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I've been doing some reading about the Scott's filters.

When you say that paper filters filter down to 10-20 microns, that's fine, (no pun intended...) but that's not the biggest particle they will pass. From what I've read most paper filters average 50-60 microns. Yes they stopped particles of 10 microns but they also passed particles of 100 microns or more.

From what I understand the Scott's claim a maximum of 35 microns will pass, nothing larger.

If they use them on aircraft rather than paper then they can't be that bad.

I know of a couple of KTM 690's with close to 90k km using them without a problem so far.

Nick.

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The only figures I have seen quoted that suggest paper filters “average 50-60 microns” are sourced from companies with a vested interest in the sales or manufacture of mesh filters. The Society of Auto Engineers figures from SAE J1858 tests on paper filters state that a “typical” paper filter has a percentage particle capture rate (efficiency) of 40% at 10 microns, 60% at 20 microns, 93% at 30 microns, 97% at 40 microns and 99.9% at 50 microns. Average efficiency being tested to be around 15 microns.

Yes a larger particle could “theoretically” get through due to the random nature of the filter media fibres, but only a tiny fraction of particles in engine oil are over 40 microns, and if there are a significant amount above 40 microns then there’s something mechanically amiss, or serious contamination has occurred, or the oil is very old – either way you’ll need to fix it and dump the oil as soon as possible whatever filter you've got. Contrary to what might be expected the more abundant small particles are much more damaging to bearings and bores than the far less numerous larger ones.

On the same terms Scott’s mesh filter’s figures would look something like this: 0% at 10 microns, 0% at 20 microns, 0% at 30 microns and 100% at 40 microns.

99% of particles in any used engine oil are <5 microns (mainly metallic residues from bearings and friction surfaces) and no filter is going to help with this; the oil deals with them by trapping them in suspension and holding them there till the next oil change. Crucially, and specific to motorcycles, are the damaging abrasive particles found in a wet clutch motor which are 20-30 micron size bits of debris from the friction plates that are too large to be held by the oil in suspension, yet will pass straight through a 35 micron mesh filter. So, the oil copes with the smallest stuff <10 microns, your mesh filter will deal with everything >35, so what’s going to deal with stuff between 10 and 35 microns?

The term “widely used in the aviation industry” is a bit of a misnomer, piston aero engines are a completely different kettle of fish; right from design through to wildly different operating conditions, most run between 50 to 100 psi flight oil pressure and have completely different service schedules from cars and bikes.

Yes, Stainless mesh filters are common in aviation. Some even have 2 micron ratings! But the operating environment is just not comparable to that of a motorcycle. Piston aero engines do not have clutches to worry the oil, flow is the more important consideration - avoiding oil starvation, the filters need to be opened and microscopically inspected at services and the oil gets changed far more regularly than any land-based vehicle. In fact the oil change interval on almost all piston engine aircraft is between 25 and 50 hours, imagine doing it that regularly on your RTW trip! Mesh filters make sense in aviation applications.

Even at automotive engine oil pressures, particles of metal and carbon are being continually forced/jammed into the filter media. In a stainless mesh filter, the particles are being wedged in the mesh screen. I’m not entirely convinced that a liberal spraying from a can of brake cleaner, or a slosh around in solvent or petrol is going to dislodge all of the particles that are firmly wedged into a 35 micron mesh at high pressure? In the aviation industry, and in military applications, mesh filters are cleaned ultrasonically, they don’t use solvents as they can’t be guaranteed to fully clean the mesh. I notice that Scott’s even say on their website that “sonic cleaning is available from the manufacturer”, which implies to me that they themselves don’t actually believe solvent washing to be sufficient in itself?

I’m not poo-pooing the idea of stainless mesh filters, it is just that there is nowhere near enough independent scientific evidence (yet) to suggest that in motorcycle specific applications they are of any benefit over conventional filters. The ASTMF316 Test and the SAE Bubble Pont test Scott’s quote from are test procedures anyone can buy in and conduct yourself. They were conducted by Scott’s and not independently.

The most important factor is changing your oil regularly. I can see the temptation to go for a mesh filter if you’re changing your motocross bike or F1 cars oil and filters every race, or perhaps changing the oil in your Cessna every 25 hours. For most of us a good quality paper filter and half-decent oil is all you’ll ever need.

Mind you, Carl Stearns Clancy rode round the world in 1912/1913 on a Henderson which didn’t have any form of oil filter or even an oil pump for that matter!

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Thanks for the informative reply. Food for thought!!

Thanks.

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This is why I should have joined this forum a year ago - people with about three hundred times more knowledge about techie stuff than me!!

Many thanks for such a detailed explanation, Pleiades. Maybe I just need to stuff one of Gskys' sexy under-seat pods full of filters!!

Paul

Well in my case 300 times is an under estimate. Great reading!!!!

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(Now sold on, sob) 2011 Blue XT660X with gold wheels, was 26,500 km.
Engine mods: K&N Stage 1 filter, DNA Stage 2 filter, snorkel removed, Kev fuel mod fitted.
Plus: smoked Puig screen, Yam aluminium sump guard, Yamaha / Acerbis handguards, Givi Trekker aluminium side cases, Leo Vince X3 cans plus Kev front fork mod and Fender Xtender. Just fitted Michelin Road Pilot 3 tyres.

SOLD the XTX for a Super Ten 1200. And just bought a Raptor 700 so staying on here for some tips....