I used up my last mini-tub of Campagnolo grease about 30 years ago. Back then I think it cost a wallet-draining $15, but now it’s $50 for 100 ml! Is it worth it? Of course not.
I have a can of Valvoline grease I bought 30 years ago and it kept my Campagnolo hubs running smoothly all that time. Cost about $3. Those hubs are still as good as new. I repacked them only once a year.
So what is grease, anyway? It’s oil that’s held in a thickening agent, or emulsifier, usually soap. Now that’s weird. When shear forces come into play, the grease breaks down and releases its oil.
As you might have guessed, I use car oil to lubricate my chain. I haven’t bought bike oil forever. Even if you don’t change your car oil, just go to a jiffy lube shop and ask for some empty containers, which always have a dab of oil inside.
Car oil may not be the best lubricant for delicate gears, such as a Sturmey-Archer hub, but other than that, it works as well as any specialty bike oil. I would not use WD-40. It contains solvents, kerosene and liquified petroleum gas that break down oil. It’s great for loosening rusty parts though.