Indian sandstone - stain removal? Sealant?

[fathertobe]

We've got some grease stains - probably through kids spilling food - on our patio. It's Indian sandstone - sourced ethically but no idea of relative quality. Official colour is Raj Green - but it's more greyish, blueish, pinkish stuff when dry.

Any ideas on removing them? I've seen suggestions such as Resiblock but there are numerous products online.

And do people seal their sandstone patios or not? Mixed views it seems. Any recommendations, again, on what to use?

Thanks.