This is from the MDW smoke oil site:
On Color Smoke
Sorry, you'll just have to be satisfied with the best white smoke available from MDW.
Many have asked us for color smoke. Indeed, some entrepeneurs (a.k.a., con men) have over the past years gone to market to sell color smoke oil, even bragging about the various colors available.
Get real.
With the internal combustion engine exhaust, into which you inject our oil, you will always get white smoke. Those who sell you color smoke oil are pulling a fast one on you. You may see a color in the oil, but when injected into the exhaust stream, you will get white smoke. You may end up with your plane or body stained by the oil, but you won't see color smoke. Buyer beware!
Smoke "bombs", on the other hand, may produce color other than white. These devices are available from selected hobby distributors but are not of the same family.
Maybe it really cant be done very easily[
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