I was servicing a friends old steel rigid GT from back in the days, the gear cables are original, black, almost rubberished.. I don't didn't know if I should lube them, look rustproof. What are they, should I use cable lube on them?

Old.

IGMC.

RealMan, that's not even funny, try harder.

almost rubberished

cable lube

WTF?

No harm in lubing, check outers aren't cracked and about to split…

Mb try throwing in a racist white joke.

I saw them and Thought.. WTF.. basicly he's not done much miles on it, shame it's such a nice bike. as for cable lube, http://www.bikeradar.com/gear/category/tools/cycling-tools/chain-lubricant/product/cable-magic-31090

Teflon coated?

Or maybe just really old solidified grease/oil?

It its been sat still that long it could probably do with new cables.

It's black through it's length so doubt it's solidfied grease/oil, the brake cables are silver.. Seems like a special cable with rubber impregenanted.. it's been kept well and ridden on Sunny days to work occasionally, though it's near 15 yrs old, the chain has .5% wear.

Oh that was until his brother borrowed it and we went cycling from Edinburgh to Glasgow through thunderstorm and all on canal path :p. Hence the service.

Mb it is just teflon coated.. similar to http://www.wiggle.co.uk/p/cycle/7/Transfil_Black_Snake_Gear_Cable_Set/5300005632/#more

No harm in lubing

You might want to pop that nugget of advice in this thread also.