Best Practice for an Oil Change

[Kupde]

Interested in everyone?s thoughts on an oil change. I always fly then do a change with hot oil but.... My RV-10 has been in the paint shop for about 6 weeks in Tampa. When it comes out it will need an oil change and I?m concerned about starting it up with the old oil now with condensate and acid build up. The question is should I dump it cold and put in fresh or do my normal practice and go fly for an hour before changing?

Thanks

Kevin

[Robert Anglin]

You can always warm the engine on the ground with a good long run-up and warming. Cold aircraft oil at 50 weight is kind of thick and viscus. Warming it will help it drain and hopefully pick up some of the unwanted stuff so it drains with the warm oil. Warming the crank case before you drain will also help dry some of the condensate that may be on the walls of the crank-case or help mix it in to the warm oil then to be drained. Your call, just ideas here. Yours, R.E.A. III # 80888

[mbauer]

Why not pre-heat the engine? A couple of hair dryers will warm it up quick. That is what I use for winter flying.

Two hair dryers in the cooling inlets and one down below where the exhaust pipes are, aimed at the oil pan.

For your purpose one at the exhaust ports aimed at the oil sump should do the trick.

Best regards,
Mike Bauer

[RV6_flyer]

Best practice is to fly the airplane, get to operating temperature, then change the oil when you land.

All the other suggestions work but ...

Do you want best practice or just some clean oil in the engine with whatever old oil and sludge left in it with the clean oil?

[lr172]

Originally Posted by RV6_flyer

Best practice is to fly the airplane, get to operating temperature, then change the oil when you land.

All the other suggestions work but ...

Do you want best practice or just some clean oil in the engine with whatever old oil and sludge left in it with the clean oil?

First, a cold engine will have more oil in the pan than a warm one, therefore a more complete drain. It takes hours for all of the oil that is going to leave the engine parts to drip into the pan. You can observe this by checking the dipstick after shut down and then again before you fly next. Not sure how hot oil will drain the pan more fully than cold, though it will do so faster due to the lower viscosity. If you are most concerned with maximum oil removal, do it when cold.

Second, it is not a problem to leave small amounts of old oil in the pan. The oil's lubricating effectiveness has a usefull life, WAY longer than our drain intervals. We change it so often, because it quickly becomes saturated with debris, such as lead, carbon, and oxidized oil and once saturated, will increase sludge build up.

Last, the oil keeps debris in suspension and it does this equally effectively at any temperature. If it didn't, all of the debris would fall out during periods of non-use and form sludge. Sludge is typically formed when oil is fully saturated (the disspersents hold debris in suspension, but can only hold so much) and any further debris falls out and settles on parts. The oxidized oil component of the debris is very gooey and helps form a syrup/paste that clings. An oil change, whether at 0* or 200* will not pull sludge out of the engine. Non-saturated oil can occasionally pick up particles from the sludge and hold them in suspension. However, this happens while the engine is running and has nothing to do with the oil change process. Most sludge, once formed, is VERY difficult to remove without mechanical cleaning or agressive solvents. It's primary evil is that it hampers the oil's ability to remove heat from the parts with sludge, as well as plugging small passages.

I am not suggesting one method or the other. Just pointing out some facts to help others with informed decisions.

Larry

[RV8Squaz]

Originally Posted by Kupde

Interested in everyone?s thoughts on an oil change. I always fly then do a change with hot oil but.... My RV-10 has been in the paint shop for about 6 weeks in Tampa. When it comes out it will need an oil change and I?m concerned about starting it up with the old oil now with condensate and acid build up. The question is should I dump it cold and put in fresh or do my normal practice and go fly for an hour before changing?

Thanks

Kevin

It depends what your goal is, whether it?s to get rid of the condensation and acid buildup or just get the oil to flow a little easier from the sump. Even if you change the oil before flying, the condensation will be there until the engine is brought up to operating temperature. The SB,

https://www.lycoming.com/sites/defau...e%20Action.pdf,

states on page 3 of the Oil Change Procedure to:

?1. Operate the engine until the oil temperature stabilizes and then shut down the engine.?

I respectfully disagree with each of the first two responses as they would likely be ineffective in getting the oil temperature to stabilize. Also, I don?t see the purpose of the ground run if your concern is condensation and acid buildup. If you?re going to do a ground run, you might as well go fly. Also, the higher rpm of flying will splash oil around more effectively. I agree with Gary... Go fly the airplane and then do the oil change in the comfort of your own hangar. Personally, I like to fly it for 30 minutes. A trip around the pattern is usually insufficient to bring the oil up to operating temperature.

[RV8Squaz]

Originally Posted by lr172

First, a cold engine will have more oil in the pan than a warm one, therefore a more complete drain. It takes hours for all of the oil that is going to leave the engine parts to drip into the pan. You can observe this by checking the dipstick after shut down and then again before you fly next. Not sure how hot oil will drain the pan more fully than cold, though it will do so faster due to the lower viscosity. If you are most concerned with maximum oil removal, do it when cold.

Second, it is not a problem to leave small amounts of old oil in the pan. The oil's lubricating effectiveness has a usefull life, WAY longer than our drain intervals. We change it so often, because it quickly becomes saturated with debris, such as lead, carbon, and oxidized oil and once saturated, will increase sludge build up.

Last, the oil keeps debris in suspension and it does this equally effectively at any temperature. If it didn't, all of the debris would fall out during periods of non-use and form sludge. Sludge is typically formed when oil is fully saturated (the disspersents hold debris in suspension, but can only hold so much) and any further debris falls out and settles on parts. The oxidized oil component of the debris is very gooey and helps form a syrup/paste that clings. An oil change, whether at 0* or 200* will not pull sludge out of the engine. Non-saturated oil can occasionally pick up particles from the sludge and hold them in suspension. However, this happens while the engine is running and has nothing to do with the oil change process. Most sludge, once formed, is VERY difficult to remove without mechanical cleaning or agressive solvents. It's primary evil is that it hampers the oil's ability to remove heat from the parts with sludge, as well as plugging small passages.

I am not suggesting one method or the other. Just pointing out some facts to help others with informed decisions.

Larry

Larry,

Doing the oil change on a cold engine goes against the Lycoming SB above. Step 2 in the procedure states, ?2. Wait at least 15 minutes after engine shutdown. Drain oil from the engine as follows?. This is for the purpose you state, to get a more complete oil change.

Usually, by the the time I get the airplane in the hangar, take the cowl off, and collect my tools, the 15 minutes have past. The procedure also states, ?E. Collect an oil sample per your spectrographic laboratory?s oil collection procedure. Be sure to collect the sample within 30 minutes after engine shutdown.?

When in doubt, I always refer to manufacturers? published guidance and procedures.

[BillL]

Originally Posted by RV6_flyer

Best practice is to fly the airplane, get to operating temperature, then change the oil when you land.

All the other suggestions work but ...

Do you want best practice or just some clean oil in the engine with whatever old oil and sludge left in it with the clean oil?

+1 Fly, then drain. Preheating and draining is ok in a pinch, but not good as a standard practice. Always take the sample for analysis after flying and hot.

[lr172]

Originally Posted by RV8Squaz

Larry,

Doing the oil change on a cold engine goes against the Lycoming SB above. Step 2 in the procedure states, “2. Wait at least 15 minutes after engine shutdown. Drain oil from the engine as follows”. This is for the purpose you state, to get a more complete oil change.

Usually, by the the time I get the airplane in the hangar, take the cowl off, and collect my tools, the 15 minutes have past. The procedure also states, “E. Collect an oil sample per your spectrographic laboratory’s oil collection procedure. Be sure to collect the sample within 30 minutes after engine shutdown.”

When in doubt, I always refer to manufacturers’ published guidance and procedures.

I don't disagree with that approach and is how I usually do it. As I mentioned, I was not recommending either, just presenting some data and clearing up misconceptions.

Larry

[Jesse]

I always recommend flying before changing the oil. I?ve seen sumps with a 1/2? of sludge because it was always changed cold. Only in very rare occasions will I change oil cold.