1. Understanding viscosity grade of mineral single grade oil
AeroShell single grade oils are available in different viscosity grades. The following table provides approximate guidance for using AeroShell Oil based on the average ambient
outside air temperature at engine start-up.
Single Grade Oil
AeroShell Oil 80
AeroShell Oil W 80
AeroShell Oil W 80 Plus
AeroShell Oil 100
AeroShell Oil W 100
AeroShell Oil W 100 Plus
AeroShell Oil 120
AeroShell Oil W 120
Temperature °C (°F)
-17 to 21
(1 to 69)
16 to 32
(60 to 89)
Corresponding SAE Grade
AeroShell SAE Grade 40, 50 and 60 oils are mineral single grade oil (both the ashless dispersant ‘W’ oils and the W Plus oils). The viscosity index of these mineral oils
is fairly uniform due to the nature of the base oils used.
This means that whilst higher grade oils such as AeroShell Oil W 100 and AeroShell Oil W 100 Plus oil may be satisfactory for operation during warm weather, it may well become
too thick to pump effectively at the lower temperatures experienced at start up. Conversely, if lower grade oils such as AeroShell Oil W 80 and AeroShell Oil W 80 Plus oil are used during hot weather, it may not prove to be viscous enough to support the loads
required when at elevated operating temperatures.
This is the reason many engine manufacturers advise that the oil grade is changed as climatic temperatures change. You should always refer to your engine manufacturer’s recommendations
for clarification on which grade to use at which temperature.
2. Understanding semi-synthetic formulation in multigrade AeroShell Oil W 15W-50
The concept of multigrade oil is to have an oil which can be used in all temperature (i.e. it’s viscosity changes less with temperature). In this way in cold weather it will
pump effectively, but still support high load at high temperature. And in warm weather, it supports high load without a compromise by having reduced viscosity. The ideal solution to this is to use an oil which has a higher viscosity index.
Semi-synthetic oils use a blend of mineral oil and synthetic hydrocarbon oil. Due to the naturally high viscosity index of synthetic oil – its viscosity changes less with
temperature as compared to mineral oils.
Another advantage of using a semi-synthetic oil is that the synthetic component of the oil has a higher thermal stability and therefore degrades at a slower rate than mineral
oils. This leads to the oil both performing as an effective lubricant for longer, and also producing less acidic compounds, the by-products of oil degradation.
The following chart shows the typical temperature to viscosity of AeroShell W Oils:
[Chart showing the typical temperature to viscosity of AeroShell W Oils]
3. Understanding the additives in AeroShell Oil W 15W-50 formulation
A load carrying anti-wear additive is blended into AeroShell Oil W 15W-50 and AeroShell Oil W 80/100 Plus. The additive does not react until it is needed. The way this works
is that if two moving parts start to make contact, then friction causes heat to be produced – this heat causes the additive to alter its chemical structure and it then reacts with the metal surfaces, coating them with a protective layer. If the two moving
parts then try to make contact again, then they are separated by a layer of the additive even if no oil is present. In this way the additive is only deposited where it is needed. This is particularly useful in limiting wear when lubrication is marginal, such
as on engine start up and on components which experience unusually high load – typically cams and cam followers. This has also been recognised by Lycoming and the additive is classified under the name LW16702, and is mandated for use in some of their engines.
Therefore, using AeroShell Oil W 15W-50 means that no additional additive needs to be used if you operate one of these engines.
“Metal passivator” additive is added and reacts with the surface of copper components found in piston engine, forming a protective layer which separates them from the oil,
thus preventing the copper from degrading the oil.
One more additive used in AeroShell Oil W 15W-50 and AeroShell Oil W 80/100 Plus is a corrosion inhibitor. This inhibits the formation of rust in the engine – a common root
cause of engines not reaching TBO (Time Between Overhaul). Rust is often found in engines as used oil is acidic and, combined with dissolved water from the atmosphere, causes corrosion.
4. Benefits of using AeroShell Oil W 15W-50
✓ Year-Round Product Solution
·Multi-grade Technology (The 25 Second Advantage) – Protects critical engine parts on start-up by reaching full pressure in the front gallery more than 25 seconds faster
than competitive oils
✓ Plus Technology Additive Package
·Corrosion protection which is particularly useful in engines which are not highly utilized
·Contains Lycoming approved LW16702 anti scuffing additive that provides superior protection against wear
✓ Semi-Synthetic Blend
·High viscosity index allows use in any season or geography year round
·The synthetic portion of the oil does not degrade as quickly as mineral base oil, is able to withstand higher temperature, and improves the viscosity index of the
5. Oil Changeover
AeroShell Oil W 15W-50 is compatible with all our single grade ashless dispersant W and Plus oils. Follow your engine manufacturers’ recommendation for oil changeover.
The steps below are provided as a general guidance:
a.Allow for oil temperature to stabilize after engine shut down.
b.Drain oil after cooling down period following engine shut down.
c.During oil change, replace or clean consumables as necessary, such as oil filter, oil screens, lock wires and gaskets.
d.Add AeroShell Oil W 15W-50 as recommended by engine manufacturers.
e.Carry out oil level check.
f.Complete pre-flight checks as required.
Possible observations during oil changeover:
a.Slightly lower oil pressure because the oil flows more easily with the semi-synthetic blend.
b.Slightly lower oil temperatures seen on the gauge due to the excellent properties of reducing heat
c.Higher time engine might notice a slightly higher engine consumption rate due to blowby because the oil flows better than straight grade products
6. Exceptions to the use of AeroShell Oil W 15W-50
Always confirm the oil selection in accordance with the aircraft engine OEM instruction. Although there are significant benefits of combining a multi-grade oil with a synthetic
component and including corrosion and anti-wear additives, there are a few exceptions.
AeroShell Oil W 15W-50 is not an option for the following:
·For “break-in” or first oil use of majority of engines (for some turbo-charged engines, refer to engine manufacturers’ recommendation)
·In Radial Engines (except small, American radials when operated in very cold climates)
·In helicopters with wet rotor clutches, which use engine oil in the clutch (predominantly piston engine Bell helicopters)