Here is my data.  88 vanagon been converted to r134-1 a few years ago.

Before.  Running 220 high side pressure, no leaks......97 degrees and humid
outside.  vent thermostat read 75 degrees...........

After.  38 pounds low side pressure, 95 degrees outside, 58 out of the
vents..  Once it got down in the 80's the next day, and the thing blew 48
out of the vents.

When I first put the red tek in, at idle, you could not see the difference.
But when you drove it, the needle came right down, and now it gets that cold
at idle.  Maybe the gas and the old oil in the init needed to combine or
something.

I bought the stuff directly from red-tek.........$7 a can, and $6 to ship
it.
Adam P
81  Westy "The Brick "
70 Single Cab "Whitey"
74 Beetle "Ol Yeller"
73 Transporter (STILL at paint shop)
1988 Vanagon Wolfsburg
1976 Transporter (New CA bus)
1974 412 "Goldmember"
Used Vanagon Parts for sale (mostly aircooled)