Piper Cherokee oil usage

[Jim K]

On the topic of oil usage, why do maintenance shops insist on putting 8 quarts in the engine when doing the oil change?

Because they aren't pilots/aircraft owners who understand the engine blows out the first 1/3 of the oil.

 

[Racerx]

On the topic of oil usage, why do maintenance shops insist on putting 8 quarts in the engine when doing the oil change?

They're not the ones cleaning it....or they also offer a detailing service that needs the work.

 

[Bob Noel]

On the topic of oil usage, why do maintenance shops insist on putting 8 quarts in the engine when doing the oil change?

perhaps because that's what the oil change maintenance instructions for say to do?

 

[Gary Ward]

On the topic of oil usage, why do maintenance shops insist on putting 8 quarts in the engine when doing the oil change?

So they can bill you for the extra oil.
Also not to be accused of sending you on your way with a low oil level crankcase.

 

[Bell206]

why do maintenance shops insist on putting 8 quarts in the engine when doing the oil change?

Simply to stay in line with the requirements of Part 43.13 and its associated references. Its also the same guidance owners are required to use when they perform their own oil changes via prevent mx.

 

[AV8R_87]

Its also the same guidance owners are required to use when they perform their own oil changes via prevent mx.

So, legally, when I change my own oil I am required to put 8 quarts in, even if I know that two of them will be blown out of the breather in the first couple hours?

 

[Bell206]

So, legally, when I change my own oil I am required to put 8 quarts in, even if I know that two of them will be blown out of the breather in the first couple hours?

Yes. Performing the oil change is considered maintenance which requires following a reference per Part 43.13. You could use the catch all reference of “…other methods, techniques, and practices acceptable to the Administrator,” to make your case for using 2 quarts less, but you leave yourself open when the OEM states otherwise as shown below.

However, once the aircraft is back flying and during a pre-flight you notice you need oil, you can service it to whatever level you want, legally, as “preflight” items like refueling and servicing engine oil are not considered to be maintenance at that time. It’s the same reason you can have the line-boy add a quart of oil and refuel the aircraft with no regulatory issues.

Now how you blur the line between the above paragraphs is totally up to you. From my standpoint, I put in 8 quarts or whatever the OEM states, enter it as such in the record, and call it a day.

 

[Dixiebluesky]

The engine manual gives you the max capacity of the sump and a minimum oil level. You are to add the appropriate amount of oil, not the max capacity of the sump. If you don't change your own oil just specify how much you want in it. If some joker insists on filling to sump capacity go to somebody else. I have never actually had a mechanic argue that he needed to fill to sump capacity.

 

[AvNavCom]

The engine manual gives you the max capacity of the sump and a minimum oil level. You are to add the appropriate amount of oil, not the max capacity of the sump. If you don't change your own oil just specify how much you want in it. If some joker insists on filling to sump capacity go to somebody else. I have never actually had a mechanic argue that he needed to fill to sump capacity.

Exactly this. It says "correct quantity" not "maximum quantity". Unless the OEM has some guidance somewhere specifying that the oil sump must be filled to maximum capacity, common sense says that the "correct quantity" is the one that exceeds the minimum quantity without negative side-effects (like blowing it out of the engine). I've never maximum filled after an oil-change in my life and if an A&P does the oil change, I specify as the owner/operator how much oil goes in (usually 7qts, to allow for oil filter capacity). My bird is max 8qts, minimum 2 qts, and happiest at 6-6.5qts. If the A&P wants to specify "7qts added per owner specifications" to cover themselves, I'd be fine with that. Doesn't seem necessary though.

 

[Bell206]

Exactly this. It says "correct quantity" not "maximum quantity".

So given the “correct quantity” reference is from a Lycoming bulletin applicable to all its direct drive engines, in the context of signing off an oil change, how would you determine what the "correct quantity" will be for an O-235 vs a GO-480?

Unless the OEM has some guidance somewhere specifying that the oil sump must be filled to maximum capacity, common sense says that the "correct quantity" is the one that exceeds the minimum quantity without negative side-effects (like blowing it out of the engine).

Here’s TCMs guidance. They use “specified capacity” vs “correct capacity” but it means the same. Same drill. Determine specified capacity for an A-65 vs an O-200?

 

[AvNavCom]

So given the “correct quantity” reference is from a Lycoming bulletin applicable to all its direct drive engines, in the context of signing off an oil change, how would you determine what the "correct quantity" will be for an O-235 vs an GO-480?


Here’s TCMs guidance. They use “specified capacity” vs “correct capacity” but it means the same. Same drill. Determine specified capacity for an A-65 vs an O-200?

Well, since I'm an owner/operator and not an A&P (but trying to do the right thing), I'd go to the guidance I'm aware of. The POH for my 1966 Cherokee 180C just says to check that "the engine oil is at the proper level" on preflight, and in the general maintenance section only specifies the maximum sump capacity and minimum safe quantity, without any reference to needing to fill to maximum capacity during maintenance. Section 2-73 in the Piper Cherokee Service Manual says "The oil sump should normally be filled with oil to the mark on the engine dipstick" but doesn't specify *which* mark. Minimum? Maximum? The only reference I can find in AC 43.13-1B to oil capacity is for weighing purposes, which notes that full oil is used for the weight calculations.

In the absence of the OEM actually giving a number of quarts for "the specified level" or the "correct quantity", I think the 'reasonable person' interpretation would adding sufficient oil for safe flight, above the specified minimum oil level. So I guess my stance is that without anything actually specifically requiring filling the sump to maximum capacity, it's ultimately a judgement call. Since I have final responsibility for the condition of the aircraft, my judgement is that the oil level should be above the minimum safe quantity but below that which my experience tells me the engine will reject as an over-fill. If someone wants to question that, I invite them to show me the guidance that specifies maximum fill and overrides my authority as the owner/operator.

 

[Let'sgoflying!]

Rather than always having the oil at "minimum", should one not consider the oil consumed on the next flight?
Ie, the oil should not be lower than minimum upon landing?
So if minimum is 6qts and your consumption is as high as 0.5qts/hr (as allowed by Lyc SB 480F, in some engines) does that not mean for a 3hr flight, to not depart with less than 7.5qts?

 

[Bell206]

Well, since I'm an owner/operator and not an A&P (but trying to do the right thing), I'd go to the guidance I'm aware of.

When you as owner/operator exercise your ability to perform prevent mx, ie., an oil change, you have to follow the same rules as an A&P. And for an oil change that starts at Part 43.13(a) and requires the use of the OEMs maintenance manual or ICAs. So that excludes the use of the POH for mx.

Since you referenced Piper’s oil change process above, we’ll follow that one for your 180 which meets the requirements for 43.13(a). Working our way down through that process we come to the para. 2-73 you mentioned above. In that same 2-73 paragraph “the quantity of oil required” is referenced in Table II-I. And that Table gives us 8 quarts which is the same “correct quantity” referenced by Lycoming in their oil change process bulletin I posted.

Now, with your oil change signed-off as servicing with 8 qts, your Part 43 mx responsibilities are done, and your POH comes back into play. And as I mentioned earlier, the FAA does not consider certain pre-flight items to be “maintenance” and you can service your oil level as you see fit.

While you may still not agree with this explanation that’s fine. But in the context of my original answer, this is the reason why mechanics, in general, service oil levels to the “correct or specified quantity” as listed by the OEMs to remain in line with 43.13(a).

 

[AvNavCom]

While you may still not agree with this explanation that’s fine. But in the context of my original answer, this is the reason why mechanics, in general, service oil levels to the “correct or specified quantity” as listed by the OEMs to remain in line with 43.13(a).

Fair enough. I'm not intending to be argumentative; just giving my thoughts on it. I agree that para. 2-73 references Table II-I, which in turn states 8 quarts is the sump capacity. I just don't like that at no point do they ever say plainly "fill the sump to capacity", instead saying "fill to the dipstick line". Seems needlessly obtuse from the OEMs. If the standard is to fill to sump capacity following an oil change, just say so plainly in the guidance. Appreciate your expertise and explanations.

Rather than always having the oil at "minimum", should one not consider the oil consumed on the next flight?
Ie, the oil should not be lower than minimum upon landing?
So if minimum is 6qts and your consumption is as high as 0.5qts/hr (as allowed by Lyc SB 480F, in some engines) does that not mean for a 3hr flight, to not depart with less than 7.5qts?

Yeah, it's generally considered bad form to run out of oil before you run out of fuel! Haha! In my Cherokee, the max is 8qts and the minimum is 2qts, so as long as I'm above 6qts (I usually add a quart when it burns down to that level or slightly lower) on preflight, even a shocking oil consumption of 0.5 qts/hr would mean I ran the tanks dry before the oil got dangerously low. Of course, if my engine is burning that much oil that quickly, I'm probably already looking into maintenance actions to correct that!

 

[Dixiebluesky]

So people are actually letting mechanics deliberately overfilling the oil on a customers aircraft? Why would anybody do this? I have never met a mechanic who does mostly piston GA work that would insist on overfilling. If you call Lycoming and say "I top off my oil to 8 quarts before every flight but only land with 6" , what's wrong with my engine? They are going to tell you to stop putting 8 quarts in it. Their own guidance says:
Measure the oil level using the dipstick. Add more oil as necessary until the oil level in the engine is
sufficient.

Putting in oil you know will blow out as soon as the attitude of the engine changes is just sloppy maintenance.

 

[Bell206]

Seems needlessly obtuse from the OEMs.

Over the years I’ve learned to be thankful for anything the OEMs would put out there considering they weren’t required formally to provide mx manuals and ICAs until 1981. Was a time when all a mechanic had were an OEM owners manual/drawings, parts manual, AC43.13-1, and the Aircraft Specifications (TCDS) to provide any references. And some are still that way like a Super Cub.

Yet Part 43.13(a) still requires you to at least find/use a reference that would be acceptable to the Administrator to perform the work. Regardless, the key is to know whats out there and where to find it before you perform any mx so that when the time comes, and you “need” to produce it you won’t look like a bumbling idiot trying to find it in the moment.

 

[AvNavCom]

like a bumbling idiot

This is my specialty!

 

[flyingcheesehead]

When you as owner/operator exercise your ability to perform prevent mx, ie., an oil change, you have to follow the same rules as an A&P. And for an oil change that starts at Part 43.13(a) and requires the use of the OEMs maintenance manual or ICAs. So that excludes the use of the POH for mx.

Since you referenced Piper’s oil change process above, we’ll follow that one for your 180 which meets the requirements for 43.13(a). Working our way down through that process we come to the para. 2-73 you mentioned above. In that same 2-73 paragraph “the quantity of oil required” is referenced in Table II-I. And that Table gives us 8 quarts which is the same “correct quantity” referenced by Lycoming in their oil change process bulletin I posted.

Now, with your oil change signed-off as servicing with 8 qts, your Part 43 mx responsibilities are done, and your POH comes back into play. And as I mentioned earlier, the FAA does not consider certain pre-flight items to be “maintenance” and you can service your oil level as you see fit.

While you may still not agree with this explanation that’s fine. But in the context of my original answer, this is the reason why mechanics, in general, service oil levels to the “correct or specified quantity” as listed by the OEMs to remain in line with 43.13(a).

Yes. Performing the oil change is considered maintenance which requires following a reference per Part 43.13. You could use the catch all reference of “…other methods, techniques, and practices acceptable to the Administrator,” to make your case for using 2 quarts less, but you leave yourself open when the OEM states otherwise as shown below.

However, once the aircraft is back flying and during a pre-flight you notice you need oil, you can service it to whatever level you want, legally, as “preflight” items like refueling and servicing engine oil are not considered to be maintenance at that time. It’s the same reason you can have the line-boy add a quart of oil and refuel the aircraft with no regulatory issues.

Now how you blur the line between the above paragraphs is totally up to you. From my standpoint, I put in 8 quarts or whatever the OEM states, enter it as such in the record, and call it a day.

View attachment 139241

Well, this all just sent me down a rabbit hole of digging through all the maintenance documentation for my aircraft and engine, and finding...

Nothing.

Well, OK, I found that the sump holds 8 quarts. I knew that already. Somewhere, I've seen that you can be as low as 2 quarts, but I can't find that to save my life now.

One odd thing I found is that some people have said that on the IO-550 they have lowered consumption by putting MORE oil in than specified. That doesn't make sense to me, but that doesn't mean it's not true. Given how dirty my belly tends to get, I'm tempted to try it.

But, I think if I'm required to put 8 quarts in the airplane at the oil change, I'm going to put 6 quarts in the engine and two quarts in the baggage compartment, as usual.

 

[Bell206]

Somewhere, I've seen that you can be as low as 2 quarts, but I can't find that to save my life now.

Its usually listed in the engine owner/operators manual. However, if the engine was certified under Part 33 it may have "usable oil" limits vs a static min oil level and possibly its in the TCDS as well. Can't get anything to download at the moment but can look later if you dont find it.

One odd thing I found is that some people have said that on the IO-550 they have lowered consumption by putting MORE oil in than specified.

FYI: adding more than the stated certified capacity can cause internal damage just as not enough oil can.

But, I think if I'm required to put 8 quarts in the airplane at the oil change,

And thats totally within your ability on how you interperate the rule under your sign off. Based on my experiences, I defer to the OEM requirements unless I can substantiate a difference.

 

[RPJ2080]

You didn't mention what kind of cylinders you have. Chrome tends to use more oil and will quickly turn the oil black if not broken in optimally. I have chrome cylinders and use a quart every 3-4 hours. This is within Continental specs of a quart every hour for my engine - C90.