View Full Version : oil bath air filter maintence

09-19-2010, 01:33 PM
I changed the oil in my filter today and of course managed to spill it on myself. I was amazed at just how gritty it was. My 55 is used pretty much as a sunny-day car driven about 1000 miles a year and i had changed that air filter oil last October. I don't live in a dusty area and can only conclude that there is a lot more air born dust that i never noticed, in the air.

I guess I'm saying that it really works and all of us with these old Studebakers that desire to avoid an engine tear down should keep on top of this maintence item IMHO.

Cheers, Murray

09-19-2010, 04:21 PM
I not sure about how often the manual may have stated to change the oil in the oil bath as my Studebaker is an Avanti but here's a clip from a Wikipedia posting on the oil bath ...

An oil bath air cleaner consists of a round base bowl (http://en.wikipedia.org/wiki/Sump) containing a pool of oil, and a round insert which is filled with fibre, mesh, foam, or another coarse filter media. When the cleaner is assembled, the media-containing body of the insert sits a short distance above the surface of the oil pool. The rim of the insert overlaps the rim of the base bowl. This arrangement forms a labyrinthine (http://en.wikipedia.org/wiki/Labyrinth) path through which the air must travel in a series of U-turns: up through the gap between the rims of the insert and the base bowl, down through the gap between the outer wall of the insert and the inner wall of the base bowl, and up through the filter media in the body of the insert. This U-turn takes the air at high velocity across the surface of the oil pool. Larger and heavier dust and dirt particles in the air cannot make the turn due to their inertia (http://en.wikipedia.org/wiki/Inertia), so they fall into the oil and settle to the bottom of the base bowl. Lighter and smaller particles are trapped by the filtration media in the insert, which is wetted by oil droplets aspirated there into by normal airflow.
Oil bath air cleaners were very widely used in automotive and small-engine applications until the widespread industry adoption of the paper filter in the early 1960s. Such cleaners are still used in off-road equipment where very high levels of dust are encountered, for oil bath air cleaners can sequester a great deal of dirt relative to their overall size, without loss of filtration efficiency or airflow. However, the liquid oil makes cleaning and servicing such air cleaners messy and inconvenient, they must be relatively large to avoid excessive restriction at high airflow rates, and they tend to increase exhaust emissions (http://en.wikipedia.org/wiki/Automobile_emissions_control) of unburned hydrocarbons (http://en.wikipedia.org/wiki/Hydrocarbons) due to oil aspiration when used on spark-ignition engines.[citation needed (http://en.wikipedia.org/wiki/Wikipedia:Citation_needed)]

I believe the industry went to paper filters because they capture smaller dust particle sizes.

09-19-2010, 05:16 PM
1000 miles or once per year, whichever comes first - more in dirty/dusty conditions.
Change to a paper element filter. Not messy and traps smaller particles.

09-19-2010, 10:31 PM
Have you ever looked in the Service Manual and see what Studebaker considered a clean state (dry filter) vs. dirty state, (oil bath).????

I believe there was a discussion a bunch of months ago about which type of filter did a better job at cleaning the air.


09-19-2010, 10:58 PM
I've seen an article before on an Iveco truck that tested the dirt (silica) content in the crankcase oil after so many miles of using an oil bath versus a modern paper media air filter. The crankcase oil after having the air filtered by an oil bath had 50 to 100 ppm dirt in it where as the crankcase oil after using a paper media air filter only had 5 to 10 ppm dirt in it. Thats a 10 fold (order of magnitude) improvement.

09-20-2010, 08:17 AM
It seems clear that a switch to a paper filter is of benefit , does anyone have a paper filter conversion they have fashioned with success?

Thanks, Murray

09-20-2010, 11:13 AM
..I suspect oil will always be available vs. paper air filters....and at what cost ?