Oil Change Pondering...

[Half Fast]

So the conventional wisdom has always been to fly the plane for a while to warm up the oil prior to draining it. I'm starting to question that a bit and I'm curious what the POA collective thinks.

It seems to me that it makes sense to warm it up when using a single viscosity like 100 weight that's thick as molasses when cold. You need to get it warm to flow out of the engine. But I'm using multi-weight oil (XC 20-50 with CamGuard) and it seems to flow pretty well when cool. I've noticed that if I check the oil right after flying and then again 24 hours later, the level on the dipstick will rise by 1/4 to 1/2 quart. It appears to take several hours for all the oil to drain down into the crankcase.

So if I do the change immediately after flying, I might be leaving a significant amount of old oil in the engine. I suppose the best approach might be to start draining while the engine is warm, but let it continue to drain overnight. That's a bit inconvenient, though, and I wonder if it's really necessary with a multi-grade.

Thoughts?

 

[Salty]

I usually drain for a couple hours. Take a short flight. Open the drain. Collect the sample. Do the paperwork for the sample (gives time for the filter to drain a bit). Change the filter. Cut the filter open and inspect. Go get lunch. Close the drain. Add oil.

*edit* forgot to put *clean up all the oil I spilled changing the filter* in there before going to lunch.

 

[GeorgeC]

I usually drain for a couple hours. Take a short flight. Open the drain. Collect the sample. Do the paperwork for the sample (gives time for the filter to drain a bit). Change the filter. Cut the filter open and inspect. Go get lunch. Close the drain. Add oil.

Before you open it and collect the sample, don't forget to wipe the drain with the provided moist towelette.

 

[Gary Ward]

Years ago I let a commerical air compressor drain while I went to dinner. When I came back I had tire change on my mind and flipped on the compressor. A minute or 2 later I was thinking about how am I going to repair the pump on my compressor.
Learned a lesson that day as I never walk away from a oil change. I change oil for a living in expensive diesel engines.
I do the same with my plane. Fly it and come back and change it. I'll let it drain for 10-15 minutes and then I refill.
In the grand scheme of things a few drops of old oil is not gonna hurt your engine.
When I change oil in big truck diesels I don't even roll out from under the truck until the drain plug is back in and the new filter is installed. So it gets to drain for 5-10 minutes for 39 years now.

 

[Salty]

Years ago I let a commerical air compressor drain while I went to dinner. When I came back I had tire change on my mind and flipped on the compressor. A minute or 2 later I was thinking about how am I going to repair the pump on my compressor.
Learned a lesson that day as I never walk away from a oil change. I change oil for a living in expensive diesel engines.
I do the same with my plane. Fly it and come back and change it. I'll let it drain for 10-15 minutes and then I refill.
In the grand scheme of things a few drops of old oil is not gonna hurt your engine.
When I change oil big truck diesels I don't even roll out from under the truck until the drain plug is back in and the new filter is installed. So it gets to drain for 2-5 minutes for 39 years now.

Fair point, but I think the big bucket of oil underneath the engine with no cowl on it just might be a clue.

 

[Daleandee]

I change oil at 25-30 hours. If a pint gets recycled in the gallon and a half I put in there I don't believe that will be of great concern.

 

[Magman]

There is no way you will get all of the oil out but that is insignificant IMHO.

You really want to get any wear particles and debris removed.

My suggestion is to use a paint strainer or other filter so you can

check what comes out w/o relying on the screen or filter to do so.

Note: It’s not good if you can read the part numbers.

 

[Half Fast]

Learned a lesson that day as I never walk away from a oil change.

I put a large note on the yoke whenever the oil is drained. Can’t start the plane without seeing it. Even if I’m not planning to leave the plane, stuff happens and I can get distracted or called away.

 

[Dana]

Between oil that stays in the oil pump, cooler, and lines there's probably a half to a full quart that never gets drained... and if all the oil drained out of the pump you'd have to reprime it. By the time I'm done cleaning the screens and spills, there's not much more coming out.

 

[Half Fast]

forgot to put *clean up all the oil I spilled changing the filter* in there before going to lunch.

I think next time my first step will be to pull the plane over to my neighbor’s hangar ramp and then drain the oil....

 

[GeorgeC]

Learned a lesson that day as I never walk away from a oil change.

Yep, that killed a guy around here. Drained the oil, put on a new filter, got interrupted, went to fly, never made it home. He forgot to put the new oil in it.

 

[Capt. Geoffrey Thorpe]

My understanding was that the reason for getting things hot is not so much for the speed of draining, but to get all of the crap stirred up and in suspension and not leave it in the bottom of the sump.

But, I could be wrong.
It happened once before.
I said "no one is perfect, not even me."

 

[Bell206]

I suppose the best approach might be to start draining while the engine is warm, but let it continue to drain overnight.

FYI: Oil is changed due to contamination. The need to run the engine is to get as much contamination in solution as possible prior to draining. But no need to reinvent the wheel. Most OEMs have figured out that running the engine till the oil temp stabilizes and waiting 10-15 minutes after shutdown prior to draining, removes enough contaminates so as not to reduce the service life of the new oil.

 

[Gary Ward]

Fair point, but I think the big bucket of oil underneath the engine with no cowl on it just might be a clue.

For sure, I agree. Pretty tuff to forget working on a aircraft.
I also don't like to drain the oil galleys of oil that can happen with a extended drain. That adds to "dry" start up of a engine. The few hours of extra drops of old oil coming out is not significant but drained oil galleys are IMO.

 

[eman1200]

1) fly
2) put plane in hangar
3) open quick drain
4) place bucket under quick drain that I forgot to do in step 3
5) consume contents of beer fridge as needed
6) return next day
7) finish oil change
8) repeat step 5

 

[Gary Ward]

Yep, that killed a guy around here. Drained the oil, put on a new filter, got interrupted, went to fly, never made it home. He forgot to put the new oil in it.

Wow!
I line up my empty qts on my table as I add them. That way I know how many I put it. They sit there for a day or so until I throw them away.
I am very focused when I change oil on anything since I had a bad/costly experience. Sooner I can get that oil back into the crankcase the better.

 

[eman1200]

Wow!
....They sit there for a day or so until I throw them away....

I flip them upside down and drain them for several days, one at a time, into another container. amazing how much extra oil you can scavenge out of those things.

I remember when I was young and I thought the peanut butter jar was empty, my dad would be scraping away at the friggin thing until he got every last drop of pb out of that sucker. well, he'd get one extra samich out of it than I would have. if u add that up over time, that's a lot of pb&j's I was missing out on.

 

[Gary Ward]

I flip them upside down and drain them for several days, one at a time, into another container. amazing how much extra oil you can scavenge out of those things.

I remember when I was young and I thought the peanut butter jar was empty, my dad would be scraping away at the friggin thing until he got every last drop of pb out of that sucker. well, he'd get one extra samich out of it than I would have. if u add that up over time, that's a lot of pb&j's I was missing out on.

I used to do that at work with qts I use on cars and light trucks. But the bugs and dirt that get's mixed in makes not worth it to me. The big trucks use bulk oil out of a large tank that gets pumped in. So really don't use many qts except for my plane. Was even thinking about a drum of oil for the plane but the air powered pump is pretty expensive.

 

[mandm]

When the oil is warm, it drains faster. If you put a quart of oil in, you’ll notice probably 95% of the oil comes out of the can in what 10 seconds. If you are holding it for several minutes to get a few more drops, I don’t think that quantity is anything significant. I’m sure everything is calculated for the 50 hour intervals and leaving some dirty oil in the sump (which is picked up by the new oil).

 

[GeorgeC]

FYI: Oil is changed due to contamination. The need to run the engine is to get as much contamination in solution as possible prior to draining. But no need to reinvent the wheel. Most OEMs have figured out that running the engine till the oil temp stabilizes and waiting 10-15 minutes after shutdown prior to draining, removes enough contaminates so as not to reduce the service life of the new oil.

I guess it's not worth the trouble of flushing out the sump after the oil has drained?

 

[Gary Ward]

I flip them upside down and drain them for several days, one at a time, into another container. amazing how much extra oil you can scavenge out of those things.

I remember when I was young and I thought the peanut butter jar was empty, my dad would be scraping away at the friggin thing until he got every last drop of pb out of that sucker. well, he'd get one extra samich out of it than I would have. if u add that up over time, that's a lot of pb&j's I was missing out on.

I am the type to totally clean out the PB jars.
I used have this oil bottle halfazzed to the cart. The funnel fit in it nicely. Sometimes I would drain qts into it. But if you forget and leave it like for while then dust bugs can get in. I never made a bracket for it, still need to then I would maybe drain some qts. I do 4-5 changes a year, so a lot qts to drain. The drain/drip oil is great for gen lube but I would not put it into my engine.
Years ago at a job they had a drain thing on the wall that drained numerous qts at once. But then again bugs and dust can get it there.

 

[Bell206]

I guess it's not worth the trouble of flushing out the sump after the oil has drained?

Not really. The amount of old oil that remains in the engine, cooler, CS gov, etc., is dealt with by the current OEM recommendations based on my experience. But if its something you prefer to do it wont do any harm anything either.

Now if you were dealing with the aftermath of an engine oil contamination event, then additional measures should be taken which could include flushing the sump and addressing the items listed above.

 

[unsafervguy]

Years ago I let a commerical air compressor drain while I went to dinner. When I came back I had tire change on my mind and flipped on the compressor. A minute or 2 later I was thinking about how am I going to repair the pump on my compressor.
Learned a lesson that day as I never walk away from a oil change. I change oil for a living in expensive diesel engines.
I do the same with my plane. Fly it and come back and change it. I'll let it drain for 10-15 minutes and then I refill.
In the grand scheme of things a few drops of old oil is not gonna hurt your engine.
When I change oil in big truck diesels I don't even roll out from under the truck until the drain plug is back in and the new filter is installed. So it gets to drain for 2-5 minutes for 39 years now.

I have a prop flag that says No oil! That goes on when the oil gets drained and comes off after it’s refilled.

 

[455 Bravo Uniform]

My 2 boxes of oil sit in front of my plane while I change oil. I can’t pull the plane out without running over the boxes.

I’m getting lazy as I age:
-One day fly, de-cowl, drain oil, catch sample, take sample and filter home. Fill out sample paper work after dinner. Cut filter if I’m ambitious.
-Next day, if I haven’t cut filter, cut it. See if it’s worth it to put $125 in fresh oil and new filter back in/on the plane. Drop off sample at shipping store on the way to the airport. Inspect engine compartment for loose stuff, leaks, wear, etc. More often than not, I find something. Fill oil, attach filter, safety wire.
-Next day, confirm needed fix with A&P, make fixes. Do leak check. Re-cowl. Clean up the big messes I’ve made, clean tools, put stuff back. Fill out logbook at home.
-Sometimes an oil change will take me 4 visits (days) to the airport if I’m piddling and enjoying the weather. If not, then fly on 4th visit.

Getting the cowl on and off with the canards by myself is a bit of a chore. I need patience and to be fresh when I’m doing it in order to not scratch paint. I take it back, I’m not lazy, I just have less patience, so I quit before I start making mistakes or rush.

All at a leisurely pace. I’ve done it in 2 days if I have flying plans, and if I found no issues under the cowl.