Edit: Dont soak the strings with it, just rub some on yours fingers and it will work in.
Dont soak the strings with it, just rub some on yours fingers and it will work in.
Using a thinner string can help. I use a regular .10 set on my guitars, but with the lowest E string switched for a .42, more common with .09 sets, instead of the .46 that you usually have with a .10 set. I did it for a smoother feel and nicer tonal balance, but it would also slightly reduce harsh scratching you get from sliding on that string.

Other than that though, there's not a whole bunch you can do. You shouldn't have to oil your strings at all. It could be you're noticing the scratching sound more because you're using very high gain on your amplifier/overdrive pedal and you have high-output pickups too which are set very close to the strings. This will make incidental sounds like the scratching as you slide on a lower string or small dings as your fingers brush against other strings briefly more obvious. If your gain is that high, I would assume you're playing metal, in which case you want distortion rather than overdrive anyway; so there's a fix, if you're playing metal with harsh overdrive, try switching to distortion instead.

Smoother/faster sliding can help too. Not just for reducing this problem, but just for making your slides sound better too anyway. It's surprising how many people start their slides faster than they end them, or end faster than they start, or so on. Practise getting a nice smooth transition at a good consistent speed.

Or, if you're not trying to slide (maybe you're just sliding as a way to easily and comfortable change powerchords, for example), then you just need to get used to lifting your finger off the board more so you're not still fretting the string while you slide. This will minimise any additional noise you create while still providing you with an easy, comfortable way of switching around the fretboard.

In short: practise, refine your technique. 99% of guitar problems come solely from the person using the guitar, rather than the isntrument itself.