Airplanes and the Oil that they Use

Bill Komanetsky  December 30 2011 11:04:03 AM

So, this guide will help you understand just how much oil our aircraft really need.

How much is enough?

Most airplanes have a 'sweet spot' when it comes to the amount of oil that they want to use.  For instance,  I have noticed that my personal airplane, N21483, likes it's oil level at about 6.5 quarts.  When this level is added or reached, it will stay at this level for quite some time.  However, if you take the oil to anything over this, the airplane will burn it off very quickly and then keep 6 1/2 quarts in the pan for, again, quite a few hours.  

All airplanes are like this and it's a good idea to understand where their 'sweet spot' is located.


How much does each airplane need/want?

Below is a list of airplanes and their 'sweet spots'

Airplane Model	Minimum Oil	Maximum Oil	'Sweet Spot'	Comments
Cessna 152	4	6	4.5	If you aren't flying very far, then just leave the oil at 4 - 4.5 quarts.  If you plan on flying far, take a quart or two with you and only add it at your destination if it is below 4 quarts after landing and before take off
Cessna 172N	4	6	5	If you aren't flying very far, then just leave the oil at 5 quarts.  If you plan on flying far, take a quart or two with you and only add it at your destination if it is below 5 quarts after landing and before take off
Cessna 172P	5	7	5.5	Same comments as the 172N using the Sweet spot number of 5.5
Cessna 172R/SP	6	8	6.5	These airplanes really only need 6.5 quarts.  Keep a couple of quarts with you on your flight though
Cessna 182T	7	9	7	This airplane seems to like to sit a little bit above 7 quarts.  If you put in 9, it will quickly burn off about 1.5, closer to 2 quarts.
Piper Warrior	4	6	5	Quite a bit like the Cessna 172N, you don't have to drown these airplanes with oil
Piper Arrow	6	8	6.5	Quite a bit like the Cessna 172R/SP models.  Remember, each airplane is different, so the airplane you might be flying may need to take oil after a few hours of flying.  Add it AFTER the airplane needs it and not before.
Piper Seminole	4	6	5	These engines are a lot like the Cessna 172N engines, so their oil consumption is the same as well.  Remember though, there are two engines here, so if you plan on taking oil with you on your trip (which you should), carry twice as much as you would in a Cessna 172N
Piper Seneca	6	8	6.5	Much like the Cessna 172R/SP models in their oil consumption.  Remember, like with the Seminole, there are two engines here, so carry enough oil
Diamond DA42/NG			A bit over MIN	The beauty of this airplane is that you don't need to know how much oil to put in, just keep the oil between the MIN and MAX markers.  Between these two levels is just 1 quart of oil, so don't add oil unless you can actually see the MIN mark a bit.  Then, only add 1 Quart.  This oil is VERY expensive too, so don't waste it.

Scenario #1

You are going to fly a Cessna 152 for about an hour doing pattern work.  You need to get your landings a big better, so you'll probably be just flying around in the pattern.  You check the oil in the airplane and it is showing exactly 4 quarts.  Do you need oil?  You can check around the ground and see if any oil was leaking to make sure there isn't a problem.  You can even look inside the engine through the oil door (which you should do anyway) and you see everything is clean and oil free.  

So, do you need oil?  No you do not!  Have fun getting your landings cleaned up and enjoy the flight

Scenario #2

You are going to fly a Cessna 172R too Auburn airport to get some breakfast.  When you look at the oil, you see that there is exactly 6.5 quarts in the engine.  

So, do you need oil?  No you do not!  Have a good trip to Auburn, but it might be a good idea, since this is a longer trip, to put a quart or two in the baggage are of the airplane to  make sure you don't run out of oil.  Check the oil level before you leave Auburn to come back to Livermore to make sure that there is enough oil.  If you notice, at Auburn, that there is less than 6.5 quarts, go ahead and add a quart.

Scenario #3

You are going to fly the Twin Diamond (DA42/NG) on a long cross country tip and when checking the oil in the right engine, you cannot see the MIN marker, but you notice the oil is close to the MAX marker.  It is obvious that you DO NOT need oil in the right engine.  However, when looking at the left engine's oil level, you notice that you can see the top of the letter 'M' wheree the MIN marker would be.  

So, do you need oil in the left engine?  If your flight is going to be more than an hour on way, the answer is YES.  Add just one (1) quart, and no more.  If you are just going to be flying around the pattern, then oil may not be necessary.


In Summary?

You don't need to drown the airplane in its own oil, but you do need to keep it lubricated.  Take oil with you on your trip and don't over fill it.  Also remember that each airplane is different and the older an engine gets after last overhaul, the more oil it may use.  Since you don't know exactly how much oil the airplane will use up on your trip, keep some with you and check the level before you begin your return trip back to Livermore.

Another good idea is to check oil levels EVERY time you plan on starting the engine.  If you keep oil with you and you do this, you will NEVER be caught with too much oil or not enough oil.

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