I wouldn't recommend it, as GIF preloader could not load as fast to be useful, at least at the first visit. Current animation, are CSS animations, so they are pretty small.
However, I think you could do such trick: 1. In Appearance → Customize → General settings → Page preloader set Type to none. 2. Set your background color for preloader. 3. Upload your GIF animation Background image.
Comments
I wouldn't recommend it, as GIF preloader could not load as fast to be useful, at least at the first visit. Current animation, are CSS animations, so they are pretty small.
However, I think you could do such trick:
1. In Appearance → Customize → General settings → Page preloader set Type to none.
2. Set your background color for preloader.
3. Upload your GIF animation Background image.
I have just tested it, and it works sweet.
With kind regards.