For low voltage DC systems, including multi-conductor connectors like that used in your mighty, if powerful, 1993 Volvo 240, you would use a non-conductive, or dielectric, compound or product that both dissolves and prevents the corrosion that forms at bonded contacts anywhere on your Volvo 240.

So, made by Caig Company:

https://caig.com/deoxit-d-series/

Available at many outlets both brick and mortar stores as I like. Maybe also get at Walmart.com like outlets. Or maybe on Amazon.

The spray with a straw is maybe the best bang for the buck. The corrosion dissolving and corrosion inhibiting compound persists for a long time. If you have a small, unused pump sprayer with fine spray control, getting the full strength DeoxIT-D in the bottle and diluting it with 91% isopropyl alcohol will work.

Also, the action of disconnect / spray / reconnect is best. You can also merely wet the bonded contact location, like the backside of the fuse panel, as the spade connectors at the wire harness ends secured at the factory to the fuse panel spade terminals get a little frail after nearly 30 years of service.

I found this out when the 1990 240 DL li'l red Wagon had no power window action. The load side spade terminals (fuse 10 and 12) had enough corrosion to halt the power windows. I removed a few of the wire connectors and the spade connectors broke on removal. So, have spares. A spray- gentlest of wiggles - spray with spade connector removal may work also.

I had a spray can of DeoxIT-D. Was helping a guy with his late 1988-1990 740. He had electrical issues. It was at the relay and fuse platform. So, spray wiggle spray. He either procured the spray can or I left it. At any rate, I'd not replaced the DeoxIT-D spray can in nearly a decade or so.

Also, I apply dielectric silicon grease in the form of SuperLube brand NLGI 2 grease to the taillight flexi circuit boards and bulb sockets lightly. Don't get on the bulb glass envelope.

Not sure how much heat it needs.

Though begs the question why we do not have a copper alloy negative VDC ground ring or loop through the 240 unibody for electrical device connection. Sheet and plate carbon steel are not the best conductor as is used through 240 unibody for negative or ground connection like for fuel pumps and taillights. I guess works well enough.


As for the Gardner Bender OX-800 OX-Gard Anti-Oxidant Compound c1800 suggests:
https://www.gardnerbender.com/en/p/OX-800/Ox-Gard-Anti-Oxidant-Compound

IS conductive. So, you smear that stuff, say at your ABS connectors, or engine control connectors at the ECU or the wire harness connectors under the dash, it can and will form a short across sterminals at the connector. Other problems will result that can cost you some serious dough $$$.

Also, the conductive oxidation prevention stuff that uses zinc as an abrasive to break corrosion should not be used on copper connector. There is No-OX and other stuff for AC power applications using copper bonded contacts.

Sometimes this sort of conductive, corrosion-inhibiting paste is used on very high current, high voltage copper DC lug hardware such as solar or wind farm connectors that connect to battery electrical storage systems. Yet the conductive metal in the paste is copper also, not zinc. Yet I go on so .... sorry.
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For the grease used on connectors, if that’s what you’re referring to I use this.

https://www.amazon.com/Gardner-Bender-OX-800-Anti-Oxidant-Compound/dp/B000BOCBCA/ref=sr_1_1?keywords=Ox-gard&qid=1557022152&s=gateway&sr=8-1