What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Minimum oil temp before takeoff - cold weather break in

jcarne

Well Known Member
Patron
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!
 
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.

Larry
 
Last edited:
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!
 
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....
 
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.
 
Caution!

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.
 
I’m 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.
 
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.
 
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.
 
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....

In those old days, I lived in Northern Minnesota (now live in Central Minnesota...gonna keep moving south until I get warm). A sump heater, and especially a cylinder band heater, and especially a sump heater AND a cylinder band heater on a cell-remote switch is a much more elegant solution than I could ever have dreamed of back then.
 
You'll get lots of opinions on this. Most say oil must be 100* <snip>
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. <snip>
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.

Larry

100F for me is to avoid that red flashing light for over pressure oil on the panel on takeoff, nothing else. And from an engine standpoint that probably is the only thing that would cause any failure if extreme. Pressurized oil to the journals is just to cool the bearings as oil heats with shear, so that is not an issue.

I would agree with the 60-70F for start, I did the same at the same temps for my Phase I.


BTW the piston/wall clearances are made for running very hot, on a hot day and flying into a heavy rain and shrinking the barrels without seizing the pistons. This has happened. This is one reason there is more piston rattle on the aircraft engines. I know for a fact, it (the rattle) is why the skirts are thicker than normally would be needed. This is one thing I noticed about all the piston/barrel clearances when I first arrived in engineering at Continental. Don't worry about take off and piston being too large.
 
Thanks for all the great replies guys! Looks like I need to invest in some sort of pre-heat. I will come up with a home brew cowl heater for the time being and get something more permanent in the not too distant future. Thanks!
 
I have Reiff bands and pads on the cylinders, sump, and oil cooler. If I turn them on before going to bed, the oil is a toasty 90-100 degrees when I arrive in the morning.

I used to use a switch control box, but when I upgraded to a 4g unit, it went bad, and I couldn’t get any support to resolve the issue.

I now use a smart plug and a Verizon MiFi in the hangar. That also gives me Internet access not only to the smart plug, but other devices I use in the hangar.

Since the airport doesn’t have any cell towers nearby, I also installed a cell repeater with a remote antenna on mounted on the roof of the hanger with earth magnets. The airport doesn’t allow drilling holes or mounting anything to the hangar. So the plate the antenna is mounted to and all the cable restraints are mounted using magnets.

This solved the issue of getting good cell signals in the hangar when the door is closed and the heater is one.
 
BTW the piston/wall clearances are made for running very hot, on a hot day and flying into a heavy rain and shrinking the barrels without seizing the pistons. This has happened. This is one reason there is more piston rattle on the aircraft engines. I know for a fact, it (the rattle) is why the skirts are thicker than normally would be needed. This is one thing I noticed about all the piston/barrel clearances when I first arrived in engineering at Continental. Don't worry about take off and piston being too large.

Thanks Bill. Good to know. So, the scuffing we often see on the walls is more likely from either carbon debris or simply the excess clearance allowing more skirt edge contact?

I'll have to look at where my high oil pressure alarm is set at. I often take off with oil temps in the 70-80* range and have never noticed excessively high OP readings with 20W50. Though I imagine a bunch of tolerance stack up could create differences between individual engines.

Larry
 
Last edited:
Thanks for all the great replies guys! Looks like I need to invest in some sort of pre-heat. I will come up with a home brew cowl heater for the time being and get something more permanent in the not too distant future. Thanks!

An easy way for the short term is a milk house heater with some simple 5 or 6" thin wall, flexible metal ducting from the hardware store. Shape the ducting to fit in the cowl air exit area.
 
I have a Reiff TurboXP....heats the oil to 150 degrees overnight, will go from 20F to 75F in about 3 hours. I turn it on and off with a Switcheon. That’s a cell-connected switch that uses NB-IoT (narrow band - Internet of Things) and cost $200 including the first year of cell connection. No sims, no activation, no contract. Subsequent years are $50. Works even with cell connection too weak to make a phone call. Not an employee, just an enthusiastic customer.
 
An easy way for the short term is a milk house heater with some simple 5 or 6" thin wall, flexible metal ducting from the hardware store. Shape the ducting to fit in the cowl air exit area.

This. I've been using one on the C-170 for 10+ years, couple of Harbor Freight moving blankets on the cowling and the entire engine compartment is 80-90 degrees even in midwestern winter.

Cheap and easy. Lots of guys at our airport do this.
 
Shutters

I would look at putting shutters on the oil cooler, even temporarily.

The reason is you have to run the engine at high power settings to finish break in. Even if you take off with warm oil, once you run to high power settings for break in, the oil will cool down and the oil pressure could get really high.

I would think you would want a way to keep the oil warm during high power break in. With an o360 in the rv7 on a cold day, you should be scooting along at a pretty good clip ( a technical term)
 
I have an oil shutter with a control in the cockpit so once I'm flying it should be easy to get the temp where I want it. Just need to get it warmed up before starting.

If you see my other thread it looks like I might have plenty more time to get this figured out...

Thanks for the recommendations everyone
 
Back
Top