Welcome to the forum
Depending on what type of slide mechanism, the lubrication used is different and applied in a different manner.
Cable systems use a dry lube on the cables. Geared rails use a light lube on the gear teeth, but require inspection for dirt and debris.
All slides have seals on the edges that sweep stuff off. It's not uncommon for these to squeak, and there are spray treatments for them. I believe some members have used baby powder on them, but if you make them too "slick" they might not flip the right direction when the slide moves.
Do you know what type of slide mechanism you have and a more specific location of the squeak?
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2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.