Correct Refrigerant Oil for r12?
 

I was planning on using Bg Frigiquiet Universal oil in my r12 A/C system. But, after reading the technical data, it is only "recommended as a top-off lubricant" in r12 systems.
http://www.bgimw.com/AC2008/ACtech.html

I don't know what oil was used in the compressor when it was converted to r-134a because I don't have the records for the conversion. Just a compressor which was new in 2000, and a fitting on the A/C low side. Installing a new r4 compressor this weekend, after a good flushing and replacing the drier/txvalve, and refilling with r12.

Would Mineral Oil, 500-525 Viscosity be the right oil to pick? I assume I can get this from a Ford, GM, etc dealer or a chain auto parts store? Time is running out for ordering online because I'm doing the job on Sunday. Or would some other synthetic oil work, like an Ester POE?

That's good to know. I was going to use it based on the dieselgiant procedure. Found a local distributor from a link on your earlier thread.

I look forward to seeing what others say.

I am starting mine on Sunday too....Good to know someone else will be looking at the same thing I am in case I run into any problems.
:)

If you are staying with R12
 

I recall on the test...(you might want to confirm this) the oil for R12 is a type of light mineral oil. The PAG and ester oils are more hygroscopic (pick up water vapor) and could cause trouble. You don't need the certification to get the R12 oil, unlike the refrigerant.

Short answer - use R12 oil with R12 refrigerant, ester with R134a. The longer you vacuum pump the system before charging, the better.

what I recently learned in my latest refrigeration certification tests is this...
the POE oils are VERY VERY VERY hygroscopic. they do not release moisture at all... even down to 100microns! (never ever gonna get that low a vacuum in a car system!) so you HAVE HAVE HAVE to put in a new drier with the POE oils. DO NOT PUT DRIER IN SYSTEM until EVERYTHING else is done. you want that drier open the minimum amount of time before you start the vacuum pump. and it's NOT a good idea to put the oil in the drier.

So you would put the entire 8oz or so in the compressor?

no, that could slug the valves... an R4 has no sump... best to charge the oil into the lines, but you need a pump to do it, you could also put the oil in with the freon after you evacuate the system...

Why not the dryer?

Most posts concerning A/C work have people put 4 oz into the suction side of the compressor and 4 oz into the Drier.
Then cycle/turn the compressor for about 10 times by jumping the pressure switches to get the oil throughout the system, then charging. :confused:
There's a better way to do this?
And which side of the drier is the usual place to add 4 oz of oil before charging?

It looks like diesel giant put it into the port for the inlet from the condenser.

500- 525 visosity mineral oil is for r12 systems.

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the POE oils are VERY VERY VERY hygroscopic. they do not release moisture at all... even down to 100microns! (never ever gonna get that low a vacuum in a car system!) so you HAVE HAVE HAVE to put in a new drier with the POE oils. DO NOT PUT DRIER IN SYSTEM until EVERYTHING else is done. you want that drier open the minimum amount of time before you start the vacuum pump. and it's NOT a good idea to put the oil in the drier.
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I know this is a very old thread but I need to add oil to my compressor and was wondering why you should NOT add the oil to the receiver dryer? Won't the oil make it to the receiver dryer when the compressor is running?

Dieselgiant adds to receiver dryer but if there's a better option, please let me know.

I'm thinking about getting a big syringe and shooting the oil through the top (low side) line after removing the schrader valve.

I don't think the compressor will hold 8oz of oil. I'm sure some would spill out when I'm re-stalling the 3 bolts.

Also, any recommendations on what type of 500-525 mineral oil to buy?
FJC makes some Automobile Air Conditioning Parts of Tucson Arizona, Century Auto Air, AC Parts, AC Service and Hoses, centuryautoair.com

Thanks.

pete

Nah--DONT remove the valve --even from the low-side, Thats still at 25-50 PSI and you'll lose all your refrigerant gas, before you get the oil anywhere near it!

Why do you think it needs oil?

My system is empty. No refrigerant is in it. I just want to know how to add 8oz of oil without adding it to the receiver dryer.

Thx.

pete

I use 30wt mineral oil.
It can be purchased by the quart at O'Reilly's after about an hour of convincing the clerk you are not looking for PAG or Ester oil.
4oz in the suction, 4oz in the discharge.

Rotate the compressor by hand a few times to lube the pump for initial startup.
Drier always goes on last and do it quickly with minimal exposure to outside air.
Get a vacuum pump on the system ASAP.
Don't forget new O-rings throughout the system, unless you like adding R12 a lot. LOL

I didn't realize the compressor would hold 8oz. I'll have to make sure to keep the compressor level so none of the oil leaks out.

Should I pressurize the system with Nitrogen before pulling a vacuum?

I could pull a vacuum first, then pressurize and then pull another vacuum.

I'd like to test for leaks on a pressurized system.

Thanks.

pete