I have an old Schwinn that I bought 2nd hand. I don't know a lot about bikes. When I ride my bike after it's been in the rain, the gears CONSTANTLY slip as I'm peddling. If I use White Lightening on it - just a little bit - then it works fine. Can anyone tell me what the problem is? Is there a permanent solution so that I don't have to be afraid of the rain.

thanks

Time to change the chain. I experienced this problem and replacement was the answer.
Hockey

Since lube on the chain fixes it, it's probably the lube. White Lightning is not the best for wet conditions and tends to wear off quickly when wet. WL is a dry, wax based lube and is more suited for dry/dusty conditions. You might want to consider Tri-Flow or an oil based lubricant. These types have more tenacity in the rain.

I typically ride dry/dusty conditions, so I couldn't recommend a lube for wet conditions.

Perhaps others will provide recommendations.

True. Finish line XC wet is good.

You might really want to change the chain and possibly the chainrings/cassette. it may be worn down real bad

check for sticky link. shift the rear der to the smallest cog, then backpedal the cranks slowly. if you find a "hop" in the chain as it goes around the cog of pulleys, that's your culprit.

While wear is certainly possible it does sound odd that it goes away.

To check for chain wear:
Get a ruler and place tension on your chain. Like hold the back brake and force the pedal, that will stretch it if there is any. Place the ruler beside the chain. If the center of the pins on the end lines(1" and 12") are more than about 1 notch off(1/16" or so), the chain is effectively done. Some sources say up to 1/8" but the more dramatic the figure the more the other stuff such as your cogs and cassettes suffer. If it is seriously out of spec, then consider getting a new cassette.

All mechanical items have a finite life and wear with use. An improperly lubricated chain accelerates wear on itself, and mating chainring/cogs.

How you use your bike (short trips to the market or weekend enthusiast or world competitor) should also dictate how you solve the problem. One of my basic philosophies is "do the easy/cheap things first". So try a lube better suited for the wet than White Lightning. A bottle of Tri-Flow probably sells for $4 and a bottle of Finish Line XC Wet (thanks mtbikerinpa) probably goes for $8. If that solves the problem, and you're happy, then you're done.

If not, you may have to invest in a new chain ($15), cassette ($40), chainrings ($??), frame alignment ($??).... And, you'd already have the lube for the new chain.

What you are experiencing is a syndrome known as "chain suck". Your best bet would be to get your machine down to the lbs and ask them to put a chain checker on it. It's only a 2 second job and will tell you right away if you need a new chain or if a bit of lube can solve your problems

I wouldn't classify it as "chain suck". Chain suck occurs when the bottom run of the chain is sucked between the chain stay and chainring. This jamming action freezes the pedal action.

Yes, suck and skip are quite different indeed.