Greetings Kyle,

It could be two problems that you are facing, or just one. As Larry mentioned, where is the oil under the dash coming from? If it's coming down from the gauge then the brass sending coil will need to be resoldered to seal the leak. If the leak is coming from the ignition switch shutoff valve located by the ignition switch, then the failure of your vacuum diaphragm has leached oil into the vac system. This happens and as long as it's fixed relatively soon it won't cause damage to the entire system. Do a quick test of the hose going to the air filter housing and pull it off and secure a white or light colored sock to it, and drive the car ten miles or so and see what the sock looks like. If it's oily then the vacuum pump diaphragm is shot and will need replacement. If the oil under the dash is coming from the ignition switch, then after you replace the diaphragm, blow compressed air into the vac lines that lead through the fire wall from the I.P. shutdown solenoid and unhook the two going to the ignition switch vac shut off to blow the oil out of this line. It may still have some residue when you are done but it shouldn't adversely affect any vacuum items in the chain. If it's the gauge that's leaking, then do a search on oil gauge repairs on this site and you should bring up my post about repairing the brass snake on the oil gauge. It's really an easy fix if you are handy and confident about removing the dash gauges and disassembling them somewhat, as well as operating a soldering gun.

Charles

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