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Old 12-11-2020, 01:21 PM
jcarne's Avatar
jcarne jcarne is offline
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 1,508
Question Minimum oil temp before takeoff - cold weather break in

Hello everyone. I am getting close to first flight which will be conducted anywhere from 10-30 degrees F most likely. When running the engine on the ground the oil temp rises painfully slow. I have been told to avoid extended ground runs on an unbroken engine so that leads to a dilemma.

What oil temp do you guys want to see before takeoff on your engine and what might be my best approach to getting it there before runup and takeoff on the first flight.

Some more detail:

-I am running Aeroshell 65 mineral oil which Lycoming recommends for 0-70 degrees F ambient.

-It is in a hangar that I usually heat to 42 F but can go higher the day before if needed.

Surely I'm not the only one that has thought of this before. Wondering what others did.

Thanks for all your help everyone!
Jereme Carne
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Old 12-11-2020, 01:33 PM
lr172 lr172 is offline
Join Date: Oct 2013
Location: Schaumburg, IL
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You'll get lots of opinions on this. Most say oil must be 100* However, most don't know why that is and why they should do it. Lycoming makes no such recommendation. They say that as long as engine takes full throttle applicatoin without stumbling it is good to go. THey also give temp recommendations for different oil weights.

I care only about cyl barrel temp (to avoid scuffing from piston expanding faster than the barrel), which I can't measure. I wait until my CHT's are 250* and wait one minute more for the barrels to catch up. I followed the same approach with break in.

I always use a sump heater below 35* and use 20W50. I would probably have a minimum oil temp of 60-70 if I used straight wt oil.

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Last edited by lr172 : 12-11-2020 at 02:56 PM.
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Old 12-11-2020, 01:41 PM
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F1Boss F1Boss is offline
Join Date: Aug 2006
Location: Taylor Texas
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Default Well...

You should probably pull the engine thru before you open the hangar door. You might want to add a Reiff heater to your engine, and a heavy blanket - to keep the heat in the night before flying...keep in mind your job is to get to the runway ASAP after getting the engine running. It is likely you will not get to optimum temps without some more help - might be you concentrate on that for the next week or so. A tent-like thermal containment setup might with the overnight pre-heat too.

Good luck - this ain't Rocket science!

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You know who you are."
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Old 12-11-2020, 02:38 PM
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Ironflight Ironflight is offline
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In the bad old days, in a Minnesota winter with a J-3 on skis, we’d drain the oil at night, and heat it on the stove the next morning before pouring it in to the engine.

I dont think I’d go to that extreme, but a sump heater sure works wonders if you want to have warm oil and a warm sump before flying in the cold....
Paul F. Dye
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Old 12-11-2020, 04:23 PM
Avanza Avanza is offline
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Smile Lycoming break in instruction

Read this.
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Old 12-11-2020, 04:57 PM
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rv8ch rv8ch is offline
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Location: LSGY
Posts: 3,570
Default sounds good

Sounds like you are good to go. Warming up the engine a bit more can't hurt. I typically wait until I start to see movement on the gauge (>59f) before taxi, and then wait until >95f before run-up.
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Old 12-11-2020, 06:18 PM
scsmith scsmith is offline
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Location: Ashland, OR
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Even if you warm the oil in the sump, the oil in the oil cooler can be very cold. So you can start, and get partially warmed up, and then the vernatherm opens and dumps a bunch of very cold oil into the engine.

I once departed from Reno Stead in a Citabria in the winter, very early in the AM. I warmed up until I saw something like 125F on the oil temp gauge, and departed. As I turned cross wind, I got a low oil pressure light. I immediately pulled the power back and turned downwind. About the time I was mid-field downwind, the pressure came back up and the temperature registered on the gauge again.

That engine ran a long time, so I don't know if I hurt it. On overhaul years later, it was found that a couple of rods were slightly bent. I don't know if my cold-departure event caused that or not.
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Old 12-11-2020, 06:32 PM
Paul K Paul K is offline
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Location: Grand Rapids, MI
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Iím located in Michigan so have the same issues. I installed a pan heater and on the wall, an internet controlled power switch. The plane is in an unheated hangar so I turn the heater on via cell phone about a day ahead of start. I cover the whole front of the RV with an old king sized comforter, tucking it into all the cowl openings etc. Yesterday on a 27 f degree morning the oil was at 90f when I arrived. Held my hands under the comforter doing my pre flight to warm them.

Oil temps around 90 at start and 115 plus after a short taxi to the runway. I would recommend this method to anyone living in a cold climate.
Paul K
West Michigan

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Old 12-11-2020, 07:30 PM
birddog486 birddog486 is offline
Join Date: Mar 2016
Location: WI
Posts: 138

Jereme, was the engine ran at the shop after it was re-assembled?

Remember it was ran at the factory and the initial run does quite a bit of the initial ring seating on steel cylinders.

If you think you want to get the oil temps higher but the cylinder temps are headed past 325 before takeoff, just shutdown and let it cool for 10 min. The oil wont cool nearly as fast as the cylinders.
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Old 12-11-2020, 07:44 PM
Canadian_JOY Canadian_JOY is offline
Join Date: Aug 2007
Location: Ontario, Canada
Posts: 2,373

Most of the posts here are on the right track. I broke in my brand-new Lycoming O-360 on its first flight where I had to wait for OAT to warm up to -15*C so I know the challenges of cold-weather engine break-in.

Without question DO NOT run the engine on the ground to warm it up.

Invest in some form of engine pre-heater. Pre-heat the engine, the entire engine, so it's ready to fly. Then start up, taxi out, do a quick run-up, then blast off without delay.

I went with a Reiff Turbo XP system (including oil cooler heating pad) and have no regrets - it just works. That, and an excellent engine blanket from Aero-Covers (their Thinsulate-lined blanket fits like a glove and is neither heavy nor bulky so I carry it in the aircraft for winter ops). This is a permanent system because I live in the frigid north and winter temperatures are something we have to deal with for pretty much half the year, every year. With winter being a harsh reality I figured there was no sense in cheaping out and doing the job half way. I've also invested in a cellular wifi modem and smart switch to allow me to control the engine preheat from my cell phone. I feel SO spoiled.

You don't have to spend that kind of money, of course. Get some form of heat in the cowl and some means of insulating the cowl against heat loss. It really, truly ain't rocket science. Preheat so the engine thinks its summer time and your cold-weather operational challenges will be minimalized.
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