The answer to that question varies greatly, depending on how the oil was distilled. Some top-heavy oils are bound to lose their 'charm' as they grow older if the heart and base segments are not solid and complex enough. Let me explain.
In reality, oud doesn't have anything to do with 'top notes.' At least not in the same way bitter orange, rosewood, lavender, and black pepper do; these are proper 'top notes' so far as perfumery is concerned. From the point of view of a perfumer, the word 'oud' never comes up when talking about 'top notes' going into a blend. Oud is a
base note. Just like sandalwood. And vetiver. And musk. – So, what are we really talking about when we talk about 'top notes' in a pure oud?
In reality, the top notes are the crux and apex of the so-called 'auxiliary' notes. You know how they say about traditional Indian oud that you need to 'give it 10-15 minutes' for it to 'open up' and the funk to 'go away?' Well, that applies not just to Indian oud, but to ALL oud, traditional & modern, conventional & unconventional. The 'top notes' are a byproduct of distillation: that particular set-up's chemical interactions with the feedstock as it cooks. Distillation is very much like alchemy, where you can take a piece of wood that smells nothing like fruits or vanilla or 'algae' and
coax these notes out of that wood by subjecting it to a series of chemical interactions.
As a general rule: Unless the 'top notes' smell like the piece of wood itself did prior to getting distilled, without any heat being applied, the top notes are a fraud. The only top notes that are
not 100% auxiliary are the ones that reflect the smell of the unheated wood prior to distillation. Period.
An oil that doesn't have these kind of top notes that are palpably reminiscent of, say, walla patta chips you've personally experienced, either raw or under extremely low heat, is an auxiliary note-heavy oil and it will likely
not mature into anything worth writing home about. Top notes are lost with age, and all you have left once the oil fully matures is the quality of the agarwood that went into the pot – that which you smelled after giving the oil 10 minutes for its 'true' character to come out.
Another way of looking at it: If the top notes do not get prolonged and keep humming well into the 'heart' phase while retaining their character intact, they're not from the wood. The wood only shows itself fully and without fail during the heart phase. Here's a crude illustration: The top notes smell like horse manure. Ten minutes in, you start to get an interesting sweet woodiness come out. The woodiness is what the wood smelled like. It (the wood) had nothing to do with horse manure. The manure is there because of the way the wood was processed. It is a chemical reaction and a byproduct of, in this case, fermentation. There are many other scenarios, such as if the wood is chemically altered in some way prior to distillation. The type of condenser that is used. The type of soaking barrel. The mineral content of the water used to soak. The mineral content of the water used to cook. Etc.
I predict that Oud Royale SL will not lose any top notes as it ages because the only top note I detect in it myself is a still note due to the relatively young age of the oil (August 2017). This still note will eventually disappear and the 'top chord' that hits you within a minute of application will become more dominant and extend deeper and deeper into the 'heart' phase, which will display characteristics of traditionally heated (medium heat) well-resinated walla chips.
As I discussed in
another thread, 'green,' 'oceanic,' 'salty,' and 'algae' have
nothing to do with the wood going into the pot. These are imaginary semblances unique to the psyche of the wearer (
especially if that wearer is you, Rasoul! =P). They are NOT in the wood. Agarwood does NOT smell like algae. And it does NOT smell like vanilla. And it does NOT smell like any other thing that comes to your mind when examining an oil. These are fictive 'metaphors' your mind supplies in order to 'explain' a new experience to itself. If you're not a distiller, you cannot properly dissect an oil's profile in order to comprehend the wood that went into its production. Saying you can do this is as realistic as me saying I can probably hammer someone's spinal chord straight if given a hammer and the right tools. Without the
experience of a spine surgeon, I wouldn't be able to do squat.
THE most deceiving thing to consider when evaluating an oil is its price tag. The assumption that something is superior because it is priced higher can lead to a kind of prejudice few noses are able to sniff through. I've smelled oils that cost thousands that I know cost hundreds to produce. And vice versa: Oils that cost hundreds which it would take thousands to reproduce. There is nothing more misleading than smelling an oil that goes for, say $350, and then another oil that sells for double that price, and assuming the more expensive oil is superior. Nothing can be more prejudicial than price.
Food for thought? Consider the price of Chugoku Senkoh. What exactly does it tell you about Chugoku Senkoh?