During the WW2 era, lots of high performance military aircraft, many with radial type engines were in the air. What type/weight of oil was generally used in the engines themselves ? The logistics of getting oils / fuels and such to remote airfield maintenance locations was very complex I would imagine. I'm thinking that standardization of these oils as feasible was probably a priority.
WW2 era US military aircraft piston engine oils
- Thread starter Electromotive
- Start date
It was typically mineral oil, straight weight 40 or 50 depending on ambient temperatures. Today's piston aviation engines aren't much different: air cooled, magneto fired, static timed, manual mixture. Not unlike giant lawnmower engines. And their oil requirements are also similar.
Not sure if you can get a full copy of this SAE paper.
Some interesting discussion here.
www.key.aero
Some interesting discussion here.
Original WW2 period RAF aero Engine Oil Sample Required
A sample of genuine period engine oil from, say, a RR Merlin of the WW2 period is required for scientific analysis by oil manufacturers and I am posting this request on behalf of a UK-based aircraft restoration and operating company.
I once talked to a WWII aviation mechanic and he was stationed in Alaska during WWII, and said they use to reduce the viscosity of the oil in the aircraft engines by adding gasoline to it.
It is also worth noting that many of those engines had a system that allowed oil to be added to the engine in flight to make up for loss. That would have made it possible to thin the oil that was in the engine more for starting and then add thicker oil during flight, but I do not know if that was done.
It is also worth noting that many of those engines had a system that allowed oil to be added to the engine in flight to make up for loss. That would have made it possible to thin the oil that was in the engine more for starting and then add thicker oil during flight, but I do not know if that was done.
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This is true, and not specific to WW-II. Large displacement radial piston engines burn a lot of oil, and many have a funnel tube in the cockpit near the panel so the pilot (or co-pilot) can add oil during long flights. For example, the DeHavilland Beaver powered by the R-985 has this.
Phillips offers a 25w-60 (50w-120) for radials today. Linkie here;
Phillips is one of the most popular aviation piston engine oils; their 20w50 is in use just about everywhere. I use it in my airplane. Aviation engines, being air cooled and using leaded gasoline, contaminate the oil long before it gets a chance to shear. So the 20w50 has the benefit of using the same oil year 'round winter and summer. Straight weight oil can be used in these engines. But then you use SAE 40 in the winter and 50 in the summer, and even so, the 20w50 is still better then SAE 40 in cold temperatures.
That said, straight weight oils have one advantage: they are thicker when cold and cling to engine internals longer after operation. So if you don't fly at least weekly, a straight weight oil may protect the engine better when it sits around not being used. This is particularly important since aviation oils don't have the same additives as car engine oils. They are "ashless" which means no Ca, Zn, P or Mg.
That said, straight weight oils have one advantage: they are thicker when cold and cling to engine internals longer after operation. So if you don't fly at least weekly, a straight weight oil may protect the engine better when it sits around not being used. This is particularly important since aviation oils don't have the same additives as car engine oils. They are "ashless" which means no Ca, Zn, P or Mg.
PS: Using multi-vis oil in these vintage WW-II engines is not necessarily a good idea. While it's a no-brainer with modern aviation piston engines, these are lower power and direct drive. The WW-II engines have much higher power output, and some have a geared drive from crankshaft to propellor. Gearing teeth are sometimes cut in a profile that can create extreme pressures and shear multi-vis oils. These or other differences could make multi-vis oil inappropriate for WW-II engines. It would require research & experimentation to find out.
I worked with an older gentleman who was a WW2 aviation mechanic. He told me that up in Alaska they would add gasoline to the engine oil so that it would start more easily in the cold. He said the gas would vaporize for the most part during flight. Adding gas was not permitted and the mechanics who got caught doing it were reprimanded for doing it. The Air Force tore some of those engines apart to see how much damage was done. No damage was found.
Is miss that old guy John. He was a true mechanic. He said they were few actual mechanics out there any more, just guys who replace parts.
Is miss that old guy John. He was a true mechanic. He said they were few actual mechanics out there any more, just guys who replace parts.
Pretty sure that was before VI improvers and hydrocracking. I heard it was mid-50s before there were any automotive multi-vis motor oils.
Not sure if you can get a full copy of this SAE paper.
Some interesting discussion here.
Original WW2 period RAF aero Engine Oil Sample Required
A sample of genuine period engine oil from, say, a RR Merlin of the WW2 period is required for scientific analysis by oil manufacturers and I am posting this request on behalf of a UK-based aircraft restoration and operating company.
I'm a bit confused by this statement:
When they say "Pennsylvania oils" do they just mean crude oil? And the flat curve is just flat when compared to everything else?
I believe Pennsylvania crudes were generally considered some of the better crudes for refining motor oils. It's probably not the same as before, but the big names were often from Pennsylvania including Pennzoil, Quaker State, and Kendall.
Pennsylvania grade crude oil is thermally stable and has a high viscosity index. It is generally free of asphalt and has only trace amounts of sulfur and nitrogen. It is also high in paraffin and other waxes making it highly desirable for refinement into petroleum lubricants such as motor oil. Its products are also valuable for use in certain hydraulic applications. By-products are commonly found in consumer goods such as cosmetics, and topical ointments.
Pennsylvania Grade Crude Oil - Wikipedia
en.wikipedia.org
Products refined from this type of oil are particularly prized as lubricants and many oil companies prominently display the fact that they use Pennsylvania Grade crude oil in their products.
Bradford, Pennsylvania is major center for the refining of Pennsylvania grade crude oil.
Of course. So multi-vis oil may be an option for those engines today. I say may, because not necessarily... depends on what that engine does to oil. Even today people run straight weight mineral oil in some of those WW-II vintage airplanes. Given what they have invested in those airplanes, I suspect they've done their homework and have their reasons.
One issue may be what's considered "straight weight" these days. I looked up what Aeroshell 100 is. They claim it's a straight weight mineral oil without any additives other than pour point depressants.
I've seen stuff sold as API SA motor oil before. However, I'm not sure if it would exactly be like motor oil was 70 years ago.
In war days it would have been straight mineral oil as mentioned above. I think it was in the 60's that a kind of detergent was added to make it an ashless dispersant oil. The weight was 100 grade or SAE equivalent of 50. The engines in airlines in the 50's and 60's used mostly 120 or W120 the W for the ashless dispersant, 120 is equivalent to SAE 60, yes some thick stuff when cold. In Washington state year round winter or summer the DC-3's with R-1830's and Convair 240 with R-2800 used W120, that was early 1970's.
I don't think there is anyone using these large engines nowdays that recomens using any sort of multi viscosity oil in them, unless some Alaska operators do so, I don't know. Oh and these oils never ever use zinc additives, nor do any aviation motor oils.
I don't think there is anyone using these large engines nowdays that recomens using any sort of multi viscosity oil in them, unless some Alaska operators do so, I don't know. Oh and these oils never ever use zinc additives, nor do any aviation motor oils.
