Expect to close on the purchase of a 1956 Cessna 172 soon. It has the original Continental O-300 with an oil screen. Was thinking of installing a spin-on oil filter adapter, but not sure of all the pros and cons.
Oil screen on O-300 vs oil filter adapter
- Thread starter Jim Logajan
- Start date
rotorwrench
Active member
In my experience, the pros/cons/economics of a filter vs a screen depend on a number conditions rather than on a singular condition.
And while the general consensus is that a filter will “clean” the oil better than an oil screen, whether your specific engine will reap the full service and economic benefits of an oil filter installation are more dependent on how you will operate/service/maintain that engine.
So without that specific info on your engine hard to give a specific input.
The engine has under 1600 hours since last overhaul. Oil analysis trend looks good to my untrained eyes (attached if interested.) The plane will probably be flown between 100 to 200 hours per year (5 person flying club.) With only a screen the oil changes would be about every 25 hours. My thinking is that if a filter adapter is installed oil change still every 25 hours but filter every 50.
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rotorwrench
Active member
Since you plan to fly over 75 hrs you are more on the benefit side of having a filter installed to include upping the oil changes to 50 hrs. However, oil change intervals are also calendar based which I believe is more important in the big picture of engine health and longevity and should be included.
So some of the principal pros of a filter install are savings on oil costs due to the increased hourly change interval, increased filtration vs hours flown, and improved oil condition monitoring via filter inspection. The principal cons are possible installation issues, a higher initial cost for installation/ROI and higher oil change costs due to filter costs. However the filter costs usually are a wash given you won’t be changing the oil as often vs a 25hr interval.
The filter cons come more into play when you fly less than 75hrs per year as any oil condition/monitoring improvements are not as evident when compared to the 25 hr change interval with a screen.
Regardless, there are many opinions on this topic, and as I noted, its my opinion this review method is only valid if you include the 4 month oil change limit as well. For example this can be easily done by breaking your flying year into three, four-month intervals. So whether you fly 1 hour or 49 hours in that 4 month interval the oil and filter will be changed. In my experience, this gives the best oil condition and the best bang-for-buck in the long run.
If you want more details or have questions be happy to post/answer.
Seven month followup:
Since buying the plane in February it is now due for its second 25 hour oil change. For various reasons the plane wasn't flown much till about June. First oil change was July 10. The rate up to the first change was averaging ~60 hr/year. It took just two months to fly another 25 hours so the average has increased to ~150 hr/year.
I will definitely ask the mechanic to install a filter adapter. Back in February I had made a note that the Tempest CO-300 adapter was available from Aircraft Spruce for $498. Today they list it for $533.
I note that Airwolf has a remote mount filter adapter for $935 (hoses not included.) The only advantage I can see it might have is if the filter could be mounted within easy reach of the generously sized cowl access panel on my old 1956 C-172. Replacing the filter without removing either of the cowl halves would be nice, but difficult to justify cost and complexity.
Since buying the plane in February it is now due for its second 25 hour oil change. For various reasons the plane wasn't flown much till about June. First oil change was July 10. The rate up to the first change was averaging ~60 hr/year. It took just two months to fly another 25 hours so the average has increased to ~150 hr/year.
I will definitely ask the mechanic to install a filter adapter. Back in February I had made a note that the Tempest CO-300 adapter was available from Aircraft Spruce for $498. Today they list it for $533.
I note that Airwolf has a remote mount filter adapter for $935 (hoses not included.) The only advantage I can see it might have is if the filter could be mounted within easy reach of the generously sized cowl access panel on my old 1956 C-172. Replacing the filter without removing either of the cowl halves would be nice, but difficult to justify cost and complexity.
rotorwrench
Active member
FWIW: not a fan of remote filters on small recip aircraft unless your filter location is a real beach to get to... which in most cases is mainly on twins in my experience.
I can see why.
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