referring initially to fig1 - 3 , the present invention provides a specially designed oil filter assembly 10 which is operatively connectable , in a subsequently described manner , to an engine block 12 of a gasoline or diesel engine . while the filter assembly will be representatively described herein in this particular application , it will be readily appreciated by those of ordinary skill in the filtration art that the assembly is also useable in a wide variety of other applications , such as in transmissions or hydraulic systems , and with a wide variety of other contaminant - bearing fluids to be filtered . the oil filter assembly 10 includes a hollow cylindrical outer canister or housing 14 having an open , internally threaded upper end 16 , and a closed lower end 18 from which an integral , generally nut - shaped drain projection 20 centrally depends . the internally threaded opening 22 of the projection 20 defines a bottom drain opening of the canister 14 . a generally bolt - shaped drain plug 24 is removably threaded into the opening 22 to close it . an annular adapter head member 26 is threaded into the open upper end 16 of the canister 14 and has a central , internally threaded circular opening 28 extending axially therethrough . opening 28 is circumscribed by an annular , inwardly projecting flange 30 through which a circumferentially spaced series of angled inlet openings 32 extend . the inlet openings 32 are sloped axially and circumferentially relative to the axis of the adapter head 26 in a manner such that , as subsequently described herein , when oil is forced downwardly through the inlet openings 32 it swirls in a vortex flow pattern about the longitudinal axis of the canister 14 . an internally and externally threaded adapter ring 34 is threaded into the adapter head member opening 28 and has diametrically opposite , radially extending driving slots 36 formed in its top side surface to facilitate this connection . directly below the adapter head 26 is an annular top screen fixture 38 having an annular top side flange 40 that is telescopingly received in the adapter head 26 and sealed therein by means of a suitable o - ring seal member 42 ( see fig2 ). top screen fixture 38 , which could alternatively be formed integrally with the adapter head 26 if desired , projects downwardly through the upper end 16 of the canister 14 and has an axially intermediate annular exterior peripheral flange 44 . removably received in a bottom interior end portion of the canister 14 is a circular bottom screen fixture 46 having a raised central circular portion 48 , and a bottom side annular peripheral flange 50 having a circumferentially spaced series of radially inwardly extending peripheral notches 52 formed therein . the engagement of the outer periphery of the flange 50 with a downwardly and radially sloping lower end portion of the canister side wall supports the bottom screen fixture 46 above the drain opening 22 , with the bottom screen fixture 46 forming a top side wall of a contaminant chamber 54 in a lower interior end portion of the canister 14 . longitudinally extending upwardly from a central top side portion of the raised central portion 48 of the bottom screen fixture 46 , and suitably anchored thereto or formed integrally therewith , is a perforated flow tube 56 having an open upper end 58 . an upper end portion of the tube 56 is slidably and removably received in the central opening 60 of a tubular bypass head member 62 ( see fig4 also ) which , in turn , is removably received within the annular top screen fixture 38 as best illustrated in fig3 . alternatively , the bypass head member 62 may be formed integrally with the overlying top screen fixture 38 if desired . with reference now to fig1 and 4 , the upper end of the bypass head member 62 has a sloping , axially inset central portion 64 which , at its bottom side , meets the central opening 60 of the bypass head member 62 that removably receives an upper end portion of the perforated tube 56 . extending between a vertical side wall portion of the bypass head member 62 and the sloping inset central portion 64 are a circumferentially spaced series of angled discharge openings 66 which , relative to the axis of the tubular bypass head member 62 , are axially and circumferentially sloped in a manner such that , as subsequently described herein , oil discharged from the bypass head member 62 swirls in a vortex pattern about the axis of the bypass head member 62 . alternatively , the discharge openings 66 may extend axially through the bypass head member 62 so that no appreciable swirl is imparted to oil exiting the discharge openings 66 . circumscribing the perforated flow tube 56 , and axially extending between the top side of the raised central portion 48 of the bottom screen fixture 46 and the lower end of the tubular bypass head member 62 is a replaceable tubular bypass filter element 68 . replaceable filter element 68 , which is operative to filter out relatively small contaminant particles ( i . e ., sub 40 micron size particles ) from oil operatively traversing the oil filter assembly 10 as later described herein , is representatively of a wound fabric construction , but could alternatively be of other constructions , such as a foam filtration material , if desired . together , the perforated flow tube 56 , the bypass head member 62 and the replaceable bypass filter element 68 form a uniquely operative bypass filter section 70 of the overall oil filter assembly 10 . of course , in an alternate configuration thereof , the replaceable tubular bypass filter element 68 may instead be constructed as a disposable filter element . in addition to the bypass filter section 70 , the oil filter assembly 10 also includes a full flow filtration section which is representatively defined by a tubular , reuseable and cleanable full flow filter element 72 which , as later described herein , is traversed by all of the oil flowing through the filter assembly 10 . full flow filter element 72 is representatively of a wire mesh construction and is operative to filter out from the oil relatively large contaminant particles ( i . e ., particles of about 40 micron size and above ). of course , in an alternate configuration thereof , the full flow filter element 72 may instead be constructed as a disposable filter element . as best illustrated in fig2 and 3 , the full flow filter element 72 is coaxially and removably received within the canister 14 and coaxially and outwardly circumscribes the bypass filter section 70 . the raised central portion 48 of the bottom screen fixture 46 is telescopingly and supportingly received in a lower end portion of the full flow filter element 72 , and a bottom annular side portion of the top screen fixture 38 , below its peripheral flange 44 , is telescopingly and supportingly received in a top end portion of the full flow filter element 72 . as best illustrated in fig3 the installed full flow filter element 72 forms within the canister 14 an annular outer flow area 74 which circumscribes the axis of the canister 14 and is disposed between the vertical interior side surface of the canister 14 and the full flow filter element 72 , and an annular inner flow area 76 which circumscribes the bypass filter section 70 and is disposed between the full flow filter element 72 and the bypass filter section 70 . the upper end of the annular outer flow area 74 underlies the angled inlet openings 32 , and the downwardly dished upper end of the bypass head member 62 underlies the central opening in the adapter ring 34 . as shown in fig2 and 3 , the oil filter assembly 10 is installed on the engine block 12 by simply rotating the assembly 10 relative to the engine block 12 in a manner causing an externally threaded tubular oil filter stub portion 78 of the engine to thread into the adapter ring 34 , and an o - ring seal 79 , carried in an annular groove in the top peripheral side portion of the adapter head 26 , to be sealingly compressed against the engine block 12 and thereby seal off an axially inset portion 80 of the top side of the adapter head 26 positioned above its annular flange 30 and communicating with unfiltered oil discharge ports ( not shown ) in the engine block 12 . the unique operation of the installed oil filter assembly 10 will now be described in conjunction with fig2 and 3 . during operation of the engine with which the oil filter assembly 10 is associated , oil 82 discharged from the engine during operation thereof is forced downwardly through the angled adapter head member inlet openings 32 and into the annular outer flow area 74 and is caused to swirl therein about the full flow filter element 72 . this swirling or “ vortex ” flow pattern imparted to the oil 82 within the flow area 74 causes , by centrifugal force , contaminant particulates in the oil to be forced outwardly toward the vertical interior surface of the canister 14 ( while partially purified oil 82 is forced inwardly through the full flow filter element 72 into the inner annular flow area 76 ) thereby permitting these contaminant particulates to settle downwardly into the contaminant chamber 54 via the peripheral notches 52 in the bottom side flange 50 . as illustrated in fig3 a major portion 82 a of the oil 82 entering the inner annular flow area 76 through the full flow filter element 72 ( representatively 90 percent or more of such oil ) is forced into and upwardly through the angled bypass head member discharge openings 66 . the oil portion 82 a upwardly exiting these angled discharge openings 66 , around the upper end of the central bypass head opening 60 , is caused to swirl about the axis of the bypass head 62 in a swirling flow pattern which creates a low pressure area similar to a tornado vacuum . this swirling flow pattern imparted to the oil portion 82 a creates a venturi effect within the inset top portion 64 of the bypass head 62 which , in turn , creates a lowered pressure region adjacent the top end of the central opening 60 . such lowered pressure region in the inset portion 64 operates to draw the remaining oil portion 82 b within the inner annular flow area 76 laterally through the bypass filter section 70 ( thereby filtering out sub - 40 micron size contaminant particulates from the oil portion 82 b ), into and upwardly through the interior of the perforated tube 56 , and then into the inset area 64 where the oil portion 82 b joins the swirling oil portion 82 a and is carried along therewith for discharge from the oil filter assembly and return to the engine via the oil filter stub 78 . as can be readily seen , the oil filter assembly 10 functions , in a single compact package , as both a full flow filter and a bypass filter , with the bypass filter portion of the overall assembly being representatively nested within its full flow filtration portion . there are no tubes required for the filtration system installation , only one external filtration device needs to be installed on the engine , and the separate full flow and bypass filtration sections are firmly supported within the canister 14 against possible vibration damage and resulting leakage . representatively , the full flow and bypass filtration sections are arranged in series , with the oil 82 flowing first through the full flow filtration portion 72 , and then flowing through the bypass filtration section 70 . by virtue of the incorporation of both full flow and bypass filtration sections in the oil filter assembly 10 , the filter assembly 10 is provided with a substantially lengthened duty cycle since it is able to filter out from the oil circulated therethrough both 40 + micron sized contaminant particulates and sub - 40 micron sized contaminant particulates . the compact and quite simple oil filter assembly 10 desirably provides the added benefit of fine particle bypass filtration without most of the disadvantages of conventional separate bypass filtration systems . referring now to fig3 and 4 , after a duty cycle of the filter assembly 10 comes to an end , the assembly 10 may be easily and quickly readied for another duty cycle as follows . with the engine turned off , the drain plug 24 is removed , and the oil in the canister 14 drained therefrom . the canister 14 is then unscrewed and removed from the adapter head member 26 to expose the full and bypass filtration sections 72 , 70 . the full flow filter element 72 is then removed from the canister 14 , the upper end of the perforated tube 56 is removed from the bypass head 62 , the bypass filter element 68 is upwardly removed from the tube 56 and discarded , and the reuseable filter element 72 is appropriately cleaned . a replacement bypass filter element 68 is installed on the tube 56 , the tube 56 is reconnected to the bypass head 62 , and the cleaned full flow filter element 72 is placed back in the canister . the canister 14 is then screwed back onto the adapter head member 26 as shown in fig2 and 3 to ready the oil filter assembly 10 for another duty cycle . the foregoing detailed description is to be clearly understood as being given by way of illustration and example only , the spirit and scope of the present invention being limited solely by the appended claims .