R134a retrofit questions?

[Dave Yentema]

hey guys, got a couple of questions about converting the ac in my car 
(875kt)

she has never been retrofitted to 134, and from lack of use 90% of the r12 
is gone, its low to the point that the comp won't even run(I tested this by 
jumping the connectors on the low pressure switch) So after weighing out all 
the options, i've decided that the conversion is my best bet right now.

I've seen my dad do the conversions before, and whenever he did it 
professionally he would just evacuate the r12, change the fittings, drop 
some ester oil in and charge it up with 134 (Even though this isn't the 
recommended procedure, it always worked) . He knows his stuff with AC, does 
everything the old fashioned way with just the manifold gauges and knows 
exactly what lines to touch, etc. Having him help me on this isn't really an 
option for this.

This is what I'm picking up:

-New receiver/drier (from AutohausAZ)
-134a retrofit kit, not the one with the oil, but its got all the fittings 
and o-rings I'd need (also from autohaus)
-Polymax2 oil http://www.autoacsource.com/store/coolzone_oil.html
-Variable orifice 
tubehttp://www.acsource.com/index.asp?PageAction=VIEWCATS&Category=273




I know that the system holds about 39oz of R12, and it'll take about 85% of 
that with 134, so about 33oz?

and how much oil does it take? I read somewhere it takes 8oz but i'm not 
sure.

also, any reason  why I can't do all of this while its getting colder 
outside? or should I wait till springtime to try and fill er up so to speak

any suggestions would be awesome