OK, time for a stupid question

[Iceman07]

I just brought home my new baby. C-170A N5740C is now at HFD.

So, I have been searching and searching, reading the POH, etc., all to no avail.

How often do you change the oil?

This is proabably one of those "everybody knows THAT" question.

TIA
Rich

[Bruce Fenstermacher]

Well that would depend on you and your preference.

The popular times are 25 hours if you don't have a filter. We normally don't on a stock 170. 50 hours if you have a filter. Then there are recommendations for calendar time if you don't fly that much. I have (till the ethanol issue) so I don't have them committed to memory.

You will also find people that change the oil every 25 hours with a filter and some just change the filter every other oil change. Some of use like helicopters some don't. Some fly high some low. Some in green planes, some in red. You get the idea.

I prescribe to the 25 hours if you don't have a filter and 50 hours if you do.

Of course the official word on this is probably in the engine operators manual which I don't have handy but I'm sure someone will and chime in with those numbers.

While I haven't given you the exact answer I've given you an idea.

And BTW by a filter I mean a spin on filter similar to what a car would have not the metal mesh screens found in the stoke 170 engine.

[tshort]

I have filters on both airplanes and change around 25 hours or 3-4 months, whichever comes first.
Oil is not too pricey, I enjoy the work, and it gives me a chance to open the cowl and look the engine and accessories over. My car has >200K miles on it and I'm sure is in part due to frequent oil changes.
My buddy gives me a hard time and wants me to save the oil I drain at 25hr to use in his plane!
To each his own, I guess.

Thomas

[N2865C]

I have filters on both airplanes and change around 25 hours or 3-4 months, whichever comes first.
Oil is not too pricey, I enjoy the work, and it gives me a chance to open the cowl and look the engine and accessories over. My car has >200K miles on it and I'm sure is in part due to frequent oil changes.
My buddy gives me a hard time and wants me to save the oil I drain at 25hr to use in his plane!
To each his own, I guess.

Thomas

ditto

[Bill Hart]

My oil consumption is so high I use the jet engine method. I just clean the srcreen and keep adding.

[N73087]

Don't obsess about pricise timing. Remember that these engines represent some of the best technology to come out of the 1930's.
I change my oil and filter every time a 50 or 100 comes up on the tach. I am confortable with plus or minus 10% if it is more convenient. I send out a sample for analysis. I change the air filter element every time 100 comes up.
BTW, I learned to fly at HFD, way back before they had a tower. We called across the river to Rentschler for an altimeter setting.

[flat country pilot]

Bill,

WOW, what do you consider high oil consumption? What is average oil consumption?

Iceman07,

There are no stupid questions, just dumb mistakes.

Bill

[GAHorn]

The service interval originally called for (by both Cessna and Continental) was for a 25 hour oil change. This was also called for in the Owner's Manual in the "Care - - Responsibilities" or Service section. (Look for the lubrication-points illustration to see the 25 hour oil drain recommendation.)
The 100 hour Inspection is also described in the Owner's Manual, and specifies an oil drain and screen inspection every 100 hours. (But most mechanics recommend you inspect the screen every time you drain the oil. This is because the screen has no by-pass capability, and if clogged, will cause the engine to starve for oil. BTW, we are talking about the "pressure" screen...the one with the larger diameter. The smaller "suction" screen is an extremely coarse screen only designed to catch tools which were left inside during engine assembly or, as some like to say, "parts large enough to have part numbers on them" like magneto gears, etc. The suction screen ordinarily does not need to be inspected except at overhaul.)
The pressure screen will likely have lots of black particles trapped (carbon from coked oil which flakes off the undersides of piston-domes) and sometimes a sliver or two of aluminum or copper/brass. Those types of minor particles are OK as long as they are just few and far between. But any ferrous items (iron/steel) which can be picked up by a magnet need to be shown to your mechanic. Wash the screen with solvent in a clean container and strain it thru a coffee filter is one method that works.
(TIP: A dark particle that shatters when put on an anvil and struck with a hammer is carbon. One that flattens is metal.)
Like Bruce says, a spin on filter is better than any screen. They have paper elements that actually trap dirt. Screens only "screen" out large dirt clods....until they dissolve into fine dirt particles....then they circulate again. If you don't have a spin on filter, you will have to buy an adaptor and STC which provides approval for it's installation on your engine. My preference is FM Enterprises http://www.fm-enterprises.com/ but there are others out there also. Don't fall for the ones that claim to be better than spin on filters. They're just finer screens...they are not capable of holding dirt. (A certain brand-name that begins with the letter "O" comes to mind, as an example of the type to avoid.)
It's important to use only the filter specified by the STC. Some adaptors have internal bypass valves...and some do not and require filters that have the bypass valves integral to them.
Spin on filters supposedly double the ordinary oil-change intervals, and sometimes also make claims that the filter is only necessary to be replaced every other oil change.... but I don't agree with the idea of running clean oil thru a dirty filter. I always change my filter when I change my oil. (But I also adhere to the original 25 hour oil change recommendation despite the fact that I have a spin on filter. I don't fly my 170 that much...a 100 hours a year is about tops, and most recommend that regardless of operating hours, a seasonal/3-month oil change is needed. (It's probably true that long-term idle periods with dirty oil is probably worse than operating with dirty oil, due to condensation/contaminates.) I don't follow that quite so rigidly, and if I get an oil change done every 25-30 hours/3-4 months, ...then I feel OK about it.
You didn't ask, but I'm so shy I sometimes fail to speak up so, since I'm typing I'll go ahead and tell you I recommend SAE 50 straight wt oil, like AeroShell 100W. In really cold winter months I may use SAE 40/AeroShell 80W. I don't ordinarily recommend multi-grades except for aircraft that fly in cold wx every day without opportunity for pre-heat.

[blueldr]

In Georges brief remarks above he, also failed to mention that he does not recommend the Pep Boys oil that I use.

[bradbrady]

In Georges brief remarks above he, also failed to mention that he does not recommend the Pep Boys oil that I use.

I realy don't want to go here!
George is right on the changing times, using Aviation oil I recomend to my people (recomend being the opertive word) no matter how many hours you fly in three months change your oil. Oil is cheep compared to a crank or cam shaft. Getting rid of that old oil is also a way to rid of unwanted condincation and asid buildups. It will help on the longevity of your engine The specs. for oil are listed on your TC sheet.
brad

[Bill Hart]

WOW, what do you consider high oil consumption? What is average oil consumption?

Iceman,

I was just joking. I change mine every 25 hours and use srieght weight oil. Down here in the south there is little need for multi weight oil.

[tshort]

Do you guys use the W100 or the W100+ ?
I know the additive is for a certain Lycoming engine, but any reason (aside from cost) not to use it?

As an aside, skygeek.com has pretty good prices on oil - free shipping if >50$ (I am not affiliated in any way)

Thomas

[Bruce Fenstermacher]

I don't use the + oil.

[blueldr]

All of you AVIATION OIL users should check both COSTCO and SAMS CLUB. The last eight cases I bought (a group buy) ran $26.00/case for Shell 15/50 Multi Vis. nd $24.00 for Shell 100w.

Pep Boys is even less!

[blueldr]

In the discussion of aviation petroleum lubricants, especially those dispensed by Manny, Moe ,and Jack, please note the prominent lump in my left cheek which is caused by my tongue.