The International Cessna 170 Association

The first quart of eight used to go out of my airplane in about the first hour too. I finally just used seven quarts and it held just fine. Never did figure out why.

I know on the truck I drove the first 1.5 qts were lost due to the crank beating the oil and I assume vaporizing. My dad chewed me out for not keeping the oil on the high mark but later moved the high mark and never lost oil as quickly. Just think of the engine positions when flying and possibly the same scenario.

John

I had what I thought was excessive oil consumption when I filled it to 8 qts. It would be down a quart after two hours. I'd add it back... it'd be down a qt in two hours.... ad infinitum...
Then on one looong flight I ran out of spare oil and didn't want to pay FBO prices when I had an oil change coming up anyway so I let it get down to 6 qts.... where it stayed for the next 8 hours.
I did the oll change and serviced it to 6 qts. I didn't have to add another quart for 8 hours. I'm satisfied with that, and my oil temps have not changed.

I have an old continental operating book that indicates the engine was designed to burn about a quart an hour. The reason for the eight quarts was so you would run out of fuel before you ran out of oil...

Almost every engine I've seen has a "happy spot", and that seems to vary by engine. Not just make/model, but each individual engine. Like others have said, experiment letting the oil go down to see if it stabilizes at a happy spot.

DEM

George,
A friend of mine converted an early C-172 to a taildragger using a one-time STC. I was doing some research regarding dipsticks for this change and ran across this thread. In it you said,

GAHorn wrote:IN FACT... if all technicalities are followed.... the spring clip is required for utilization of the increased oil-temperature limits of 240F called for in the latest TCDS for the engine, as is the retainer-chain for the oil cap.

While I see that "Note 1" in the TCDS allows for the higher oil inlet temperature when using the right spec oil, I can't find where you found the requirements for the spring clip and oil cap retainer chain. I see that this TCDS has been revised 21 times. Was that requirement in an older revision perhaps?

Gary, I’m not ignoring you…I just am suffering a bran pharrt as to the source where I found that info. I’ve lost two computers to water damage since that was discovered and I’m looking thru my paper-work records hoping I kept a physical copy. (If I were better at this I would have/should have posted the source when I posted the info.) Keep fingers crossed….

To be completely forthright, I was shocked to discover it because my own oil fill cap did not have the req’d retaining-chain. (I don’t see how that would help either.)

No sweat George, I was just curious. I too wonder why this would be required for a change in oil temperature limits. I thought maybe you found some obscure Continental Service Bulletin that talked about this but I haven’t found such a bulletin. I was also looking for the replacement dipstick part number for this 172 tailwheel conversion. It appears that one can no longer buy one from Continental as it’s not listed in the latest revision of SIL 00-7. (SIL 00-7A showed the correct dipstick for a C-170 to be 628410A1).

n2582d wrote:No sweat George, I was just curious. I too wonder why this would be required for a change in oil temperature limits. I thought maybe you found some obscure Continental Service Bulletin that talked about this but I haven’t found such a bulletin. I was also looking for the replacement dipstick part number for this 172 tailwheel conversion. It appears that one can no longer buy one from Continental as it’s not listed in the latest revision of SIL 00-7. (SIL 00-7A showed the correct dipstick for a C-170 to be 628410A1).

I've been running an 1967 0-300D out of a 172 in my '53 for the 34 years that I've owned it. For the most part I've always ran 7 qts. I do let it get down to 6 on occasion but usually try to keep it between 6 and 7. With a 7 qt. fill-up upon oil change, it always reads 8 1/2 qts. on the dipstick, so I just subtract 1 1/5 qts. from whatever the dipstick reads. I suppose the correct dipstick would be nice but it works for me.

Joe
4518C