Oil chambers and weapon capsules ?

[HurinTheCursed]

Simple and triple weapon capsules from complete adventurer and oil chambers from dungeonscape seem to be the kind of emergency tricks that can be handy for martials. However, while I didn't expect a gatling wand chamber, I'm still not really convinced by what I pictured so far.

Ghost oil and ghostblight are easy ways to get ghost touch even if it lasts only 2/3 rounds. true death (lesser in that case) crystal is better if you often fight undead however.
Quicksilver also lasts 3 rounds and can be great to avoid resistance. Once again 3.5 truesilver may be better for recurrent needs and do a bit more.
Poisons are powerful mid level but require immunity for repeated use. They don't last long, cost a bit more but they impact the game.

Regarding oil, I found no rule for using plain oil as a grease to avoid grapples, magic oils in the SRD lack impact IMO.

Have you had good experience with this gear ? if so, which substance did you pick ?

[Zirconia]

Ghost oil and ghostblight are easy ways to get ghost touch even if it lasts only 2/3 rounds. true death (lesser in that case) crystal is better if you often fight undead however.

I've mainly used the ghostblight, incorporeal foes are not unusual, at least in the campaigns I've been in, and eliminating a 50% miss chance is much more damage than +1 fire or something. Since it is a free action to use the weapon capsule, it doesn't hurt your combat at all, and it lets you put other enchantments or crystals on the weapon even if you fight a fair number of undead, say an Undead Bane on the weapon and a Lifekeeping crystal for example.

[HurinTheCursed]

undead, which of incorporeal, are common enough in my campaign to get both undead bane and a lesser truedeath crystal rather than capsules (while least truedeath + capsule would be nearly similar).