Oil Change Time - How important to heat oil before draining?

[RobertGary1]

Curious why not just take a lap around the pattern?

[redraider]

Good question, but my time constraints made me change/drain the oil yesterday.  At the the time I needed to do so, it was 36015G25KTS and OVC006 and dark.  A strong cold front was passing through.     

[Piloto]

Bob

 

Next to my hangar there is an oil dumpster tank were I empty the 5 gallon container with the oil and AVGAS in it. Never heard any complaints from the company that recycle the oil.

 

José 

[Mooneymite]

I've never used avgas in my sump before.  I remember when radials were king mixing avgas with the engine oil was common place for cold weather starts.  The avgas would evaporate as the engine came up to temp.  

 

Avgas may not dilute the congealed sludge in the bottom of a flat engine very well when it's cold.  It's pretty solid unless it's warm.  I suspect the avgas will pick up the liquified top layer, leaving the sludge behind.

 

Perhaps if there were a way to stir it....?

 

Next time I remove a sump, I'll do an experiment and see if the avgas actually removes the cold sludge.

[redraider]

This will be the only the 8th oil change on this low-time-since-overhaul engine.  Hopefully it won't have the sludge buildup a 1500hr or like motor will have.  We'll see.  It's all very interesting but I could be splitting hairs when it comes to how obsessive I want the oil to be clean; how much dirty oil I can remove, etc. etc.

[RobertGary1]

On the flip side you have operators in Alaska who put thousands of hours on their engines and never change their oil. Yet their engines aren't blowing up. I've seen car motors with oil pans full of sludge after many hundreds of thousands of miles. Yet the were running well. Sometimes we over obsess in aviation. 

 

-Robert

[Andy95W]

On the flip side you have operators in Alaska who put thousands of hours on their engines and never change their oil. Yet their engines aren't blowing up. I've seen car motors with oil pans full of sludge after many hundreds of thousands of miles. Yet the were running well. Sometimes we over obsess in aviation. 

 

-Robert

Agreed. Do the best you can and try not to worry.

Our engines were designed to be able to withstand abuse. We treat them WAY better than folks did in the past. I learned to fly at a flightschool that didn't preheat unless it got below 10° F or if the engine wouldn't start, and oil changes at 50 hours. Those engines all went to TBO and beyond.

[DrBill]

my A&P tells me the airport manager got $300 for 200 gal of used oil that he collects in an old fuel oil drum.  We dump in the oil, the guy comes and pumps it out and pays the manager for having a drum there !  Easy money every few months.

BILL

[helitim]

Jose'

We were preparing to perform a 50 hour on one of the planes today. Decided to go to lunch first with our maintenance chief and our A&P IA, I mentioned your suggestions of the avgas as a sump cleaner. The A&P IA said absolutely not to do that. He was concerned of the volatility of the avgas inside the engine in the event of an ignition source. Said it could cause an explosion and potentially ruin the engine. I asked what the ignition source would be. He didn't really have a clear answer to that question.

Your idea makes sense to me but, I am still a comparatively low time aircraft pseudo mechanic so, my opinion doesn't mean much yet. Please help me to understand why there is no safety issue with this process.

Thank you,

Tim

[Piloto]

Tim

 

I can understand your concern and of those of your friends. But the chances of AVGAS vapors ignition in the crankcase are none. And even if there was one the engine crankcase is pretty rugged to contain it with no damage. Even if you throw in a lighted match the most you will get is a puff. After all the engine does 5,000 explosions per minute when running. That what is designed for. I has been doing it for over 25 years with no issues or concerns but good benefits.

 

For checking particles in the oil filter I found the following procedure to be less messy and more accurate.

 

Let the filter stand upside down on a cut soda can so it drains the oil in the cavity. Let it stand for a day.

Pour MEK into the filter to the top and let it stand for 15 minutes up right. This will dilute and dissolve the oil in the  filter element. But not the particles since they are trapped by the filter paper element fibers. 

Drain the filter completely and open the housing with a disk cutter.

Cut the filter element and unroll it to check for particles.

 

The advantage of the above is the high visible contrast of the particles against a dry clear oil filter element. No messy hands either when doing it. 

  

I do not do the oil analysis because is subject to too many variables. After all any considerable oil particles are trapped by the filter and will not go into the oil sample you submit. The filter will accumulate the last 50hrs of engine running while the oil sample is just re filtered oil of the last running hour. 

 

José  

[Mooneymite]

 He was concerned of the volatility of the avgas inside the engine in the event of an ignition source. Said it could cause an explosion and potentially ruin the engine. I asked what the ignition source would be. He didn't really have a clear answer to that question.

 

 

What does he say about the practice of mixing avgas with the oil to get a radial engine started in cold weather?

[fantom]

 Sometimes we over obsess in aviation. 

 

 

 

Somethimes.......?       

[RobertGary1]

Tim

...

I do not do the oil analysis because is subject to too many variables. After all any considerable oil particles are trapped by the filter and will not go into the oil sample you submit. The filter will accumulate the last 50hrs of engine running while the oil sample is just re filtered oil of the last running hour. 

 

José  

 

What lab do you use? I don't see those inconsistency with Blackstone. My oil analysis between oil changes are usually very consistent or a trend. I don't see the random  fluctuations.

 

I did have a piston pin plug work loose and start to rub against the cylinder. Far too little metal to ever see in the filter but the oil analysis saw it as an ever increasing tread for the prior 100 hours.

 

-Robert

[kortopates]

What does he say about the practice of mixing avgas with the oil to get a radial engine started in cold weather?

 

Your comparing the blending of a small amount of gas into large amount of oil in radial to pouring a gallon of gas into an essentially empty crankcase?

I suspect the prime candidates for an ignition source would be the same ones dictating we don't add gas from plastic gerry cans into our tanks; especially inside the hangar and why we properly ground the fuel source to the plane while refueling. Unlikely? Of course, but it has happened plenty enough to a number of people that saw their plane go up in flames from static electricity buildup while pouring gas from plastic fuel cans; especially in cold dry winter conditions. In your radial engine example, its a closed grounded system, unlike the ungrounded probably plastic gas can you're holding. Surely not meaning to pick on anyone for doing this, but its important to be aware of the risk so anyone seriously takes precautions if doing this, at least for your hangar neighbors that could include many of us!