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-   -   changing oil hot or cold??? (https://vansairforce.net/community/showthread.php?t=141922)

Mel 09-16-2016 09:30 AM

Quote:

Originally Posted by jpowell13 (Post 1112135)
I just changed oil yesterday after running the engine first. When I removed the filter, it was full of oil and made a bit of a mess. Does most of that oil drain out of the filter if the engine is not run prior to oil change? John

If all that oil drained back into the engine on shut-down, every time you started the engine it would have to fill the filter before supplying oil to the engine. You wouldn't want that!

snopercod 09-16-2016 09:46 AM

Quote:

Originally Posted by Mel (Post 1112140)
If all that oil drained back into the engine on shut-down...

Funny you should mention that. I just learned yesterday that Tempest oil filters have an anti-drainback valve (like a flapper valve) to keep that from happening. I assume other brands have something similar. Oil Filter ADB Valves
Quote:

The ADB valve?s job is to trap oil in the passages leading from the sump, through the pump, and to the filter. As long as the pump stays full of oil,
even hot thin oil, it will re-establish oil pressure almost instantly after the engine is started.

Steve Melton 09-16-2016 10:06 AM

I drain mine cold in the Summer. I don't like working around a hot engine. I have noticed slightly less oil in the filter when draining cold and I make less of a mess. Besides, my oil is still clean at 50 hrs and I wonder why I am doing this.

Jrskygod 09-16-2016 10:16 AM

On cars, boats , motorcycles, lawnmower and my airplanes i always drain it hot or at least very warm for the reasons mel elaborated. Its pretty amazing that you can check the dipstick and it looks pretty good after it has set for a week or so but when you drain the oil out its pretty ugly looking. not near as clean as the dipstick showed. If at all possible I always fly or run up the plane or use the engine for the other vehicles and then drain the oil. On my plane while things cool down and the oil is draining it is a perfect excuse to do a quick compression and timing check, clean out the air/oil separator suction tube in the exhaust, mouse milk exhaust joints and just look everything over real good. I takes me just shy of four hours to do the whole thing, cowl off to cowl on and I don't rush things. I generally don't pull the oil screen until annual time unless I find something that doesn't look right in the filter when I cut it.

Once I just pulled the cowl when the oil was cold, drained the oil, changed the filter and put the cowl back on. The plane flew just fine for the entire trip - It was amazing. I was nervous the whole time tho thinking about what i should have checked.

And about that sludge thing - just pull the oil pan on an engine that has 1000 hours or more with regular oil changes. You will be amazed the amount of **** that is in there especially the amount grey lead deposits.

vasrv7a 09-16-2016 10:18 AM

warm vs cold sample
 
Taking a warm oil sample is recommended for oil analysis... to be taken within 30 minutes of engine shutdown.

Steve Melton 09-16-2016 10:24 AM

I cut the filter after every oil change but do not send for oil analysis. What is my risk?

RV8Squaz 09-16-2016 10:26 AM

Flying to warm up the oil prior to an oil change is like having dessert before dinner!:). Why not? Also you need to do an engine run and take it for a post oil change operational check flight. Now it's like having dessert twice!

Steve Melton 09-16-2016 10:32 AM

maybe two check flights. opening my kimono, I changed my oil a week ago and did a check flight and all was good. upon the second flight with a passenger my top cowl pushed open an inch. darn it, I forgot to install the aft top cowl pins. back to the airport, install pins and continue the flight.

Auburntsts 09-16-2016 10:37 AM

Quote:

Originally Posted by Steve Melton (Post 1112166)
I cut the filter after every oil change but do not send for oil analysis. What is my risk?

An oil analysis can show trends that allow you to identify potential parts failure before they occur. Kind of like cheap insurance. For my money, it's worth the $25 it costs (Blackstone) so I can have the data. However, it is not a panacea, just another tool in the kit, so to speak.

snopercod 09-16-2016 10:40 AM

Quote:

Originally Posted by Steve Melton (Post 1112166)
I cut the filter after every oil change but do not send for oil analysis. What is my risk?

Oil analysis is an early warning system which may alert you to potential problems. I think it's cheap insurance - about $15 per analysis. I use Lab One Aviation in Phoenix and have been pleased with them. The owner even spent about 20 minutes on the phone with me one time answering a question on "high silicon". I send in each sample via USPS and they email the results back as a .pdf. They also keep a history of my engine.


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