I understand there is an excellent company out west somewhere... CA maybe... where they will convert ANY diesel, without any concern for whether it is a suitable candidate - they even use most of the tanks and things your car came with, and the service is excellent.
On a serious note, your biggest enemies are pollutants in the oil (sugar, salt, fry pieces...) and cold oil. If you arrange it to a point where your oil is always clean, and is only burned hot... I think you should be okay if dumpster diving doesn't sound like more trouble than it's worth to you.