I have a 77 caprice r4 compressor and im looking to get the ac charged with r12. Problem is know one knows for sure the correct oil or freon charge. Im guessing its around 3 lbs of freon and at least 6oz of mineral oil. I know to little oil is bad so is too much. The compressor has a sticker that says 6.0 oz I have been asking around, and i have been told it may be 8.0 oz or 7.5oz, is there a ratio of oil to refrigernt? any ideas on the proper viscosty? 500 520 525? to thick wont flow till warmed up not good, to thin may not protect as well when hot?
Thanks for any help

Unless system is empty from flushing it out or all new parts there is still oil in there. It's off my charts by age but it should hold about 8oz total from empty. Any history as to what's been done already? Oil becomes a guessing game and it can tolerate a bit too little or too much,

If you can find it look for a sticker that states the original charge weight and go by that,

T
_________________________________________

Tom Greenleaf - MetroWest, Boston

hello, i am redoing the entire system. I had it charged a few year back, and the mechanic did shotey work and $300 bucks went out the window. So i have been holding true to the old saying if u want it done right do it yourself. I put in a new condeser, evaporator, have a new drier waiting till im ready to charge system to put it in, so no moister gets in the drier, new return hose, and new pressure hose from the compressor to condesor. working on getting a new compressor, cant find the hose that goes from condesner to orafice tube, but the old one never leaked still looks in good shape. So the system will basically be new.
I purcased some of those $$$ green hydrognated butaline nitrile orings. Not sure if i spelled that right. Last guy used old rubber ones. I want to make sure verthing is doe to spec, so it last and works right for a long time.

So if the system is new & dry should take about 8 oz? And if its used and a compressor is changed should take about 6 oz?

So next step is a compressor, some come will oil in them some dont? But who knows what kinda oil there puting in it, if its not mineral oil they may think it for r134 just cause its the new standard, even thou it was normally used with r12. So i dont want to use there oil cause who know what type oil or what viscosty.

So my my situation is. What is the correct r12 refrigerant charge, what is the correct oil charge oz. And what viscosty oil is the best to use 500 520 or 525.

Thanks for you help

Are you keeping it R-12? System might hold up to about 11 oz of oil. Mineral would be for 12 and you can choose PAG 150 or Ester if you switch over. Dump out oil out of compressors new or used. You may get none out of used and either should be spun with oil by hand before you start up the system. The system capacities are off any charts I have so I hope you can find some info under the hood. Note that some replacement parts will change system capacity but should say how much on the packaging.

If you must charge this by the seat of your pants know your pressures and take your time. A cool link to charging procedures is HTTP://www.autoclimas.com/Refrigerant%20charge.php and following that will really help with the success of the job. If you click on a link hit contact us and ask for Nacho and he might have specs for that car.

T
_________________________________________

Tom Greenleaf - MetroWest, Boston