do you wait until the oil change cycle to get the sample or could one take out a little quantity in-between and top up a few quarts afterwards?
All of the oil analysis providers have their set of instructions, but basically the sample is taken during the oil change at whatever interval has been set. Some people like myself do it at every oil change whilst others only do it every 100hrs.
The engine has to be brought to temperature before in order to mix all the oils components, then the procedure reminds one of taking the medical in that about 1 liter of oil is drain before taking the sample.
A tag with the engine data, hours on the oil, oil burn rate, oil type, etc, is sent along the sample.
Sending regular probes will then yield trend tables which are one of the tools used to assess the engine’s health.
Just sample at the engine service. You write the actual age of the oil on the piece of paper.
I have never done this. So, pardon me for the dumb question: do you wait until the oil change cycle to get the sample or could one take out a little quantity in-between and top up a few quarts afterwards?
Dan wrote:
was at the hangar yesterday and the AOA bottle measures 60×41.5mm
Thanks @Dan. Seems to be a bit smaller than what we send to Blackstone. Mailing the Blackstone from CH costs 12 CHF. I doubt it will get much cheaper with a smaller bottle.
@eurogaguest1980, was at the hangar yesterday and the AOA bottle measures 60×41.5mm
Just make sure the bottle isn’t bio-degradable 
Not sure of the size, but I’ll try to remember and measure a sample bottle next I’m at the hangar… estimate 6cm tall and 4.5cm diameter, and slips in the bubble envelope provided.
This is what it says in the description: The simple kit is a 2oz sample and tested for 9 metals.
AOA “only” tests for 9 metals, but IMHO it is more than enough. Trends graphics, alarms, and values are provided. Blackstone is more expensive, and provides more in depth measurements, but I’m in no need for their romantic description of my engine’s sexual life 😉
As mentioned, I’ve been using AOA for many years on different aircraft, and they provided yet another valid and reliable tool for assessing my engine’s health.
Dan wrote:
Not a problem with AOA which I’ve been using for many years, as their bottles are small enough to not qualify as full parcel, but as “small goods max 100g” which ships cheaply and easily to the US.
@Dan, what is the sample size you need to send to AOA? Blackstone wants 75 to 100 ml. BTW, I’ve never had trouble sending to Blackstone with their sample kits, but I am on the lookout for a bottle that is a bit thinner.
Not a problem with AOA which I’ve been using for many years, as their bottles are small enough to not qualify as full parcel, but as “small goods max 100g” which ships cheaply and easily to the US.
These, and the important paper voucher can be bought either direct, or from ACS.
Shipping declaration is done for a $0.50 value and 50g in weight.
Results are usually received by email 2 weeks after mailing.
I put all this to Blackstone and this is a part of their reply
The best solution really is to just use a bottle that
you can buy there in your own country – anything with a screw-on cap is
fine. Then include one of our oil slips (available on our website) with the
sample and mail it in. I’ll put something about this on the website.
They said they tried all sorts of stuff to appease Customs in different countries…
