I'm a new proud owner of a 1977 Seneca II, and am trying to determine the right oil levels for my engines. We all know they have 8 qt sumps, and we all know that if you fill to 8 qts, you blow oil out the breather, but I am trying to figure out where my engines really want to be oil-wise. I'm trying to determine if I have an oil consumption problem, or just don't quite understand the TSIO-360's yet.
Here's what I know. I had the oil filled till the levels read 7 qts on both dipsticks. On May 17th, I flew for 0.9 hours. The next time I went out (a week later, on May 25) both engines were at 6 qts. (1 qt per hour consumed wouldn't be great.) On May 25, I flew 1.6 hours. On May 26th (20 hours later) I checked the oil levels before our flight and found the left engine a little less than 5.5, and the right, just a little over 5. At this point I suspected an oil consumption problem. I flew 0.9 again on the airplane. A few days later (well over the 20 hours from the prior readings), we read the left engine at 5.5 and the right at just under 6 qts, significantly higher than the last readings.
So far, what I think this tells me is three things: 1) The engines are gonna throw anything over 6 qts overboard. 2) The engines need a few days for all of the oil to drain back into the sump; 20 hours is not enough time. 3) Once below 6qts, my engines are not burning an obscene amount of oil.
Here's the wrinkle. I asked my mechanic to do a reset. I asked him to do an oil change. He drained, replaced the filters, and added exactly 6 qts per side, per my instructions. Then ran the engines up to check for leaks. Three days later, I go to pick up the airplane out of maintenance, and find 6 qts in the left engine, and only 4 in the right. I checked both dipsticks side by side; they appear to be marked the same. I am wondering if the dihedral, which affects the tilt of each engine is a factor here.
Does anyone have anything to share in light of this information? Can you guys set me on the right track? I've only completed flight #6 on this airplane, so am definitely new to this and still trying to figure this all out.
Dan, Just as another reference point: - I agree, 8 quarts just blows it out - 7 quarts seems to be my magic sweet spot. I add about 2 quarts, sometimes 3, over 30-40 hours. I do not use an obscene amount of oil maintaining at that level. - 6 quarts just "feels" too low, although I have no empirical evidence
Thanks for the thoughts. I can't seem to keep 7 qts in the engines for sure. Still trying to figure out how much is being consumed vs going out the breather. One other piece of data is that I discovered that the LE and RE oil dipsticks have different part numbers. Presumably this is because they are marked differently. (Which could explain why the RE read 4 qts after a 6 qt oil change.)
So more to come on that. If any of you guys happen to be able to pull both dipsticks and take a photo of them side by side , or otherwise measure the distance from the top of the cap to the 6 qt mark (or anywhere else) that would be super helpful for me. I'll probably spring the $300 for a new, properly marked dipsrick for the RE, especially if one of you guys can confirm it's marked differently. (The dipstick that was in the right engine when I bought it was hand-marked; the markings match the factory one from the left engine.)
Yep - that is exactly the prob I had. My shop filled 6 qts in each engine and I read 8 at one and less then 5 at the other (I dont know which). One dipstick is marked „LH“, the other „RH“ - it is obviously that the „L“ is for the right engine and the „R“ for the left one (right turn/left turn). I have pics compared them exactly concerning the markings, but I dont know how to upload them. @admin: Any chance to upload in any reply?
Super helpful! Thanks. I have also heard that it can take significant time for the oil to drain out of the coolers, which could be made worse if there is any sludge or otherwise gooey oil buildup in there.
I'll continue to share notes as I figure this out.
Mike Busch addresses oil levels in a webinar. He says run at a certain fraction of full capacity. It was 2/3 or 3/4- do not recall. We add oil to our -EB engines when seeing around 5.5 on the stick. Burning very little oil at those levels and happy. Newly rebuilt engines.
Additionally, postflight in the hangar we pull the sticks out halfway to allow the case the breathe out moisture a little better. This makes for easier measurements next flight too.
Never knew the dipsticks were marked. I know the engines are different, ie., one is counter, the other isn't. And one has the AC compressor bolted on it. I'll need to go look for those dipstick markings now....
Dunno if I'm stating the obvious: a significant amount of oil is hung up in the engine after shut-down. I don't look at the oil levels for accuracy after shutting down. I find I'll "gain" around a half quart letting it sit. I only track the oil levels when the engine is cold.
On my V, I only add when I'm at or below 6. On my last annual, I had them only add 6 quarts (+ 1 pint of CamGuard) and it's stayed that way for the last 12 hours.
Keep in mind, the sump is legally required to be sized for the maximum endurance of your airplane while consuming a quart per hour + minimal operating amount. On our planes, that's a minimum engine requirement of 2 quarts + 6 quarts endurance = 8. As we all know, the top of it just gets blown out.
Interestingly, I fill both of mine to 8+ Cam guard and never have to typically touch it for at least 30 hours. I just checked and I’m down around 7.75 quarts on both after 30h
