It's still available to buy, though quite expensive.

I've been looking into the logistics of running an S-RF5 on oil and I'd be curious to see if there was any perceptible efficiency increase. The problem is that there's no lip on the ball ring to keep oil inside; I've read some reports of it leaking straight out and others that claim it's fine. The Sturmey grease seems to work well, though whilst it stays on the pinions it migrates from other areas eventually. . . I find the Sturmey hubs tend to start rattling about a year after I've serviced & greased them and I assume it's because there are areas where the grease has been forced out.