What is the maximum speed at which the CVT transmission can be shifted to "L"?

First, a disclaimer. I don't know if a CVT will work the same way or not. But with a regular automatic, it's not so much speed as Watch your tachometer. Let your engine run at about 60% maximum of red-line. For example if red-line on tach is 6000 run about 3600 rpm. whatever that gear is. That way you will not damage engine by running it too fast for too long. That's about 6.8% grade and should have enough engine braking to use minimal brakes and not heat them up or damage engine or transmission.

FordNut - Thanks for the rapid response! i finally reached someone at Subaru's national customer service Phone center. (May i say that if you are a music lover of any genre, their "while you're on hold muzak" will almost certainly give you spasms of the colon.) The service rep seemed very knowledgeable. My question was clearly not one he hadn't heard before. His response was that shifting to "L" (the only option with my CVT) can be done at any speed without damaging the transmission because CVTs are chain driven. He did warn me that using the "L" option frequently will burn more engine oil because, as you said, the engine will be running at higher rpm. So, as you suggested, i'll be keeping a close watch on the tach and applying your 60% rule. i'm going up there and back tomorrow. That should tell the tale. If i should drive off the side of the mountain, odds are that i'll never communicate with you again. Therefore, just in case - thanks again for your help! tow3