this prob was on the 6cyl forum a week ago. Seems to be an epidemic? I got the same problem as described and guess what, EF farimont!

Hmm... Mines not a fairmont, but has the police pack dash (adjustable speedo, 2kmh speed increments) and the extra guages. I should add mine doesn't go very far into the red when it comes on and buzzes, it only just makes it on. My Idle is about 600 when this happens - if I up it to around 850 it goes away. The cluster seems to be the common denominator in this doesn't it? as well as the sender ov course. Maybe the senders resistance changes when the unit gets hot? Might even be a voltage thing, but you'd expect the charge to be greater after a long hot run. Going to look into this a lot further and find an answer. might even connect my multimeter into the sender circuit to see whats going on and test it for a week. Tis would at least eliminate the sender as the problem.

Another thought occured. Since I haven't heard this happening in an on/off sender switch guage setup, maybe we could add a T-piece to the existing sender hole in the block, and screw on both the variable sender, and the regular on/off one? The on/off could be wired in to control the secondary (old) oil light in the bottom of the cluster, and the variable could be used for your piece of mind, and to watch for high pressure etc.

Suggestions?