Inliners International Forums General Discussion Engines air and oil filters

There has been some discussion lately about oil bath vs. paper air filters and also of the merits of full flow oil filtering. I have been researching what was being published in the 50s and 60s regarding these topics. One of the more relevent papers was "Engine wear as affected by air and oil filters" by W.S. James and B.G Brown published in 1950 in the SAE Journal.

To paraphrase some of the conclusions:
1) The causes of engine wear can be quantified.
2) Some oil wetted air cleaners provide almost no protection against airborne dust.
3) An oil bath air cleaner will reduce ring and bore wear to 1/10 that of some oil wetted type.
4) Although the oil bath air cleaner exhibits the same flow efficiency as the 'disposable cartridge', the 'disposable cartridge' type showed a marked reduction in engine wear of the rings (1/4 to 1/5) and cylinder bore (1/2). There was also a reduction in the loss of weight of the bearings. This is with oil filter.
5) The 'pull-over' of an oil bath air cleaner may reduce engine life by several times. Pull-over being when the accumulation of dirt raises the air cleaner oil level such that dirty oil is drawn into the engine. See here for a definition of pull-over: http://www.hastingsmfg.com/ServiceTips/air_intake_filters.htm
6) Using an oil filter will reduce bearing wear by 50% or more.
7) Chrome plated top rings double the time that an engine can be operated before excessive blow by occurs and will reduce bore wear by ~75%.
5) Changine from metal mesh to filtered crankcase breather will not materially affect ring/ bore wear but will decrease bearing clearance increase by better than a third. This is without an oil filter.

It would seem that Chevrolet's oil wetted metal mesh air filters, lack of oil filter, and no crankcase air filtering was about as far from good engineering practices as you could get.

Dear Jayson;

Yeah, that's right in theory.

Back then oil was changed every 1-2,000 miles and the mesh filter oiled etc. The 'oil bath' ones were checked & serviced if needed.

Those that followed the service guide (rules) never had a problem.

I've got a 216 with 138,000 on it. The ring ridge is nill and the rod bearings within specs. I think it failed because the timing gear finally gave up.

The public (in general) doesn't care about servicing and this is why the early engines sometimes failed.

This all changed in 1963 when GM brought out the new model Chevy engine.

Happy trail.

Hi Jason,
I understand what you are saying about the results you found regarding the tests run in the 50's and 60s specifically W.S. James and B.G. Brown. They are in direct contradiction to the results of the studies I found. I guess a person believes what he believes.

Here is what I wonder: Why do K&N - supposedly the premier filter if you ask NASCAR- researchers "allow" their filter to be out performed by a crappy 70 year old oil bath air filter? And why did the wetted AMSOIL filter assembly fair so well (the best ot the 3)? And the answer is: testing methods today vs 1950, oil today vs 1950, and engines today vs 1950. So really it is a pointless argument. If there ever was a "comparing apples to oranges" discussion, it is this one. What works today in racing or on the street is a far cry from what worked 60 or 70 years ago in an environment that does not exist today nor in machines that arent made today. To me it seems academic and only theoretic as results are insignificant - not that there arent differences, but the differences are truly inconsequential.

True also.

Another factor here is the concept of; "planned obsolesence".

In the 30s & early 40s those who cold afford cars took care of them. Then the war came and no cars were built. The 46-48 model years were the same as 'pre-war' with major changes in 49 & then again in 1955.

Throughout the "muscle car" era and into the 70s America showed the whole world; 'how it was done'. Then came the "oil embargo" and the picture changed again.

Today; people change cars every few years & rarely service them. I's a different time like you said and much has changed.

Happy trails.

This is not an issue of believing one thing vs. another. The results are not 'theoretical' they are measured under defined conditions. It is not unheard of to have conflicting data in the literature. I have seen it a couple of times. Test methods, and therefore, results can vary. I do put more faith in peer reviewed journals because the burden of publication is quite high (BTDT). Much higher than your typical advertising study. Obviously, these were atypical, worst case conditions but that is how the real world tests for them. The article compares the technology as it was when the vehicle was stock (air filter, crank vent filter, oil filter). Some folks are still running around stock or nearly so; so it may be of interest to them. I don't know why you are so enamored with KnN but oil wetted mesh it is not. I wouldn't run a KnN but that is a different issue.

In my opinion the studies you cited and the studies I found are useless to anything but empirical science. They are merely anecdotal. I don't see how anyone with a science background can see it as anything but. I believe it is entirely believeing one thing vs another. I should not have said the results are "theoretical", I should have described them as not practical. The defined conditions you describe are nowhere to be found in the real world. Show me a car that is prepped like the test cars. You will travel far and wide to find one. The average car that should be tested, more than likely wasn't - making the results moot. It also seems like the studies were done decades ago - again making them moot.

I dont know how your professional trade journals are, but ours are full of conflicting data. And these are very well respected scientists, and peer reviewed, so that pretty well shoots the argument that you can put your faith in them (unless you can believe contradictary information). I dont just read one journal either, I read 7 or 8 a month.

I am not enamored with K and N. I don't give a crap about K and N. But what is more well known in performance than them?

Greetings . . .

Terms like "planned obsolescence" may be harsh when comparing the 30's & 40's with today. In those days there was a social expectation that was reflected in business - 'durable goods' where items that customers/business expected to buy/sell only once or twice in the lifetime of a person. Things like pots & pans, cutlery, silverware, a washing machine or even a car was considered an investment for a life time.

Moreover, cars were designed with the technology at hand - a technology which consumed certain parts as a part of normal operation/wear - this meant that a car needed to be serviced in order to last. Neglect it and the relatively cheap service parts fail inviting other more expensive parts to the party . . .

As for comparisons between filtering technologies from then and now - it's all about flow and effectiveness - and what effectiveness meant then versus now.

Back then filter materials were pretty restrictive when clean and went down hill fast as they got dirty. An oil bath setup could be nearly as effective but was way less restrictive. Modern filter materials flow like crazy and are way more effective in terms of the size of particles filtered . . .

But back then 'effective' was relative to the technology. Like John points out, not only were the tolerances less tight, the materials were more forgiving. Babbitt bearings were designed 'thick' in order to ingest metallic and gritty particles. Non detergent oils deposited fine particles into the pan as sludge which was scraped as a service operation.

Today we run detergent oils that suspend particles so that they can be trapped in a filter that is designed not-to-be-bypassed unless neglected. We need an air filter that keeps all but the smallest particles from entering an engine because the tolerances are super tight . . .

So are today's products built with a "planned obsolescence" mind set or is it merely a useful life?

Many of todays cars are rarely 'serviced' by the original owner. Under a lease the original owner uses the newest months of the cars life and turns it in for another. The Dealer then services it and sells it as a 'factory certified' used vehicle. The second owner doesn't face a service bill for some time either . . .

And what is serviceable and what is a worn out vehicle that is best replaced with a new one?

There was an article in "Auto Restorer" which asked the question "will the modern cars be restored?" They experimented with a Chevy Cavalier. They found the car way to complicated for a total rebuild . . . many of the parts are designed to quickly go-together but never to come-back-apart.

So what are we restorers to do? Upgrade our classics and antiques so that they don't need the 'servicing' they were designed for? It's certainly an option. But following the guidelines of the old days is an option as well - and for 1 or 2 thousand miles per year may be the easiest . . .

regards,
stock49

I didn't find them useless, I found them interesting. Certainly nothing worth getting overly excited about. Is it entirely relevent to today's vehicle? No, and I didn't claim it was. However, if you look at todays vehicles they have good air filters, good oil filters, chrome rings, and they last a long time. At least mine do but that is a small sample size.

I think that the testing was reasonable. Varying sizes of particulates were introduced into what appeared to be a dust tunnel. This is a controlled environment; something not found in the 'real world'. Several types of air filters (and lack thereof) as well as an oil filters were tested. Engine wear areas were measured (ring gap, cylinder bore, bearing weight, bearig clearance, etc). At the VERY least, it seems like a good first step for what would have probably been early industry testing.

I haven't done an exhaustive search of any one topic since I finished my thesis. There were only one or two in about a hundred with conflicting conclusions. That doesn't invalidate their work and it doesn't make it anecdotal. More likely, it wasn't fully understood (and maybe still isn't). However, each paper still adds to the body of knowledge. Pouring over all of those papers allowed me to see things that the individual authors did not. Progress is made in small, incremental steps, building off of prior work.