*I'm not a mechanic, I'm barely qualified to work on my own bike*
I space my intervals dependant on the weather, sometimes it's under 50 hours. After a particularly muddy ride I start getting itchy to clean it out.
No personal experience with alternatives, I've only used the RS oil. I've heard a laundry list of all kinds of oils people have used in their lower legs successfully though. Grease selection is more important I'd venture.
There were a couple of other threads on the procedure if you were interested:
Here's a usable vid and some notes for the lower leg service:
•Need a good quality syringe (rubber sealed plunger) for putting in oil. Small diameter hose.
•Not necessary to remove fork or clamp bike in stand. *Hang by saddle when removing lowers, flip bike over when putting in oil.*
•Remove brake caliper and secure it as far away as possible. Small amounts of oil can get everywhere.
•Wear glasses, oil can sometimes spray out under residual pressure. Even with valve core removed.
•Do not remove any bolts completely at first. Unthread a bit then tap both bottom bolts. (Gently, with a plastic hammer).
•Clean inside of lowers with dowel and rag, there's dirt in there. Special attention to channel behind foam rings. Take some time.
•Replace old foam rings with new ones. They're cheap. Old rings swelled on me when cleaned and tend to not reinstall perfectly.
(YMMV. Rockshox foam rings are available in bulk and cost less than <$2 a change. Fox rings come in a $30 kit, so maybe try and make do with alcohol on those gold nuggets).
•Reassemby checklist: Travel indicator O ring on stanchion, foam rings installed, Slick Honey on seal.
Remove seal springs, slide lowers on, reinstall springs. Sometimes it's a faff, sometimes they pop right on.
•Slide lowers all the way on, then back 1 cm to leave space for oil.
•10ml 0W30 each side. (Or whatever your fork specific requires). This bit gives me the most trouble for some reason, sliding it up and down bit helps. In the end all of the oil needs to be in the leg.
•Don't fully compress (till bottom out) fork before reinstalling bolts.
•Torque bolts to 7.3Nm.