Strange engine oil level readings
 

Drained all the oil out of the rear engine and changed the filter. Before draining, rear oil level read near 8 qts. Let oil drain overnight, so hopefully got every drop out I could.

I added 6.5 qts based on advice I've seen here, and experienced with other motors. Started the engine, got good oil pressure readings, it ran smooth, so I shut it down.

I checked the dipstick, and the oil was showing near 4 qts. I thought it would come up in few moments so I checked it again later, but still barely over 4 qts!

No oil has leaked out. In fact I cleaned the engine after the oil change. Its spotless. Why do I read 4 qts when I put in 6.5 qts???

Logic would say its the wrong dipstick, with incorrect markings. If that's true, then the 8 qt marking would be more like 10.5 qts - no wonder it was blowing out oil!

I caught all the old oil in a jerry can, so I could measure it if needed.

My next step is to verify the PN on the dipstick, but have any of you ever experienced anything similar?

I think the reason is because the original engines didnt have oil filters they had screens.
The oil filter is taking up the difference.

That occurred to me. but I don't think the filter can hold 2.5 qts of oil, can it? Also, I checked the TSIO360 engine manual, and it shows the oil filter adapter and oil filter as original design equipment. By 1978, I believe Continental was putting oil filters on most engines from the factory.

Maybe check and see if both dipsticks are the same. Cant imagine you have 2 that are incorrect.
I would go with whats on the dipstick.
I now keep my naturally aspirated engines at 6 qrts instead of 8.
Much happier w 6 now.

Thanks for the tip Philly - I agree no need to always run full of oil. Maybe on a long cross-country, but that's about the only time I can think of I'd want full oil.

Oil Level
 

Same here. I realized after the first two oil changes (and after removing lots of oil from the AC belly) that the dipsticks weren’t calibrated. We put in 8 quarts and it reads 6 quarts. Before that I thought my engines were “burning” oil but it seems it’s just been blown out the breather tube. I use the 6 quart mark now (knowing that I filled it with 8) until I can get the dipstick calibrated.

THIS^^^
I put in the remaining 1.5 qts, for a total of 8 qts added, plus a filter change. Filter was not pre-loaded with oil. Started the motor and ran it briefly, came back the next morning, and the dipstick reads 5.5 qts. So that's my new 8 quart baseline reading.

The dipsticks front vs. rear have the same initial P/N, but different letters at the end. I will continue to monitor and investigate.

If anyone has access to a TSIO-360 parts catalog, please post the proper dipstick P/N for the TSIO-360CB engines. Thanks.

Check out Continental SIL 00-7C you will have P/N 632062-20A1 or 632062-19A1 depending
on the last digits of your engine model ie TSIO360CB3. you might also check to see if the dip stick tube is coming out of the case.
Kim

Thanks Kim. The rear engine is a TSIO-360CB-6B. The dipstick currently installed is a 632062-19 BK. Photo attached.

That should be the correct dipstick
What I do is after an engine change at the first oil change I’ll put in 8 quarts and scribe a mark On the dip stick. It is always 1/4 inch below the 8 mark on the stick. The pilots run the engines at the scribed mark and the engines don’t seem to blow any out. Then at oil changes I’ll put in 9 quarts and after the run up the level will be at my scribe mark. 1 qt. goes in the filter. It’s the same on all 5 of our 337’s

How much oil?
 

Years ago I drilled down on this: Why 12 qts when it is happy w 6?

For certification, the engines have a max allowable oil burn rate.

At that max allowable oil burn rate,
when the aircraft on its longest flight,
it must still land with enough minimum oil.

So the max endurance of the airplanes increases the oil requirement.

Ta da!