Correct Refrigerant Oil for r12? - PeachParts Mercedes-Benz Forum

derburger · #1 08-07-2008, 01:15 AM

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?

zeke · #2 08-07-2008, 08:19 AM

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.

C Sean Watts · #3 08-07-2008, 08:29 AM

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.

vstech · #4 08-07-2008, 09:03 AM

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.

zeke · #5 08-07-2008, 11:59 AM

Quote:

Originally Posted by vstech

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?

vstech · #6 08-07-2008, 12:59 PM

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...

Matt L · #7 08-07-2008, 01:10 PM

Why not the dryer?

derburger · #8 08-07-2008, 01:41 PM

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.

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?

zeke · #9 08-07-2008, 02:35 PM

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

TOPGUN · #10 08-07-2008, 10:54 PM

500- 525 visosity mineral oil is for r12 systems.

petecooke · #11 05-20-2013, 10:50 AM

**********************************************************************************
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.
************************************************************************************

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

Alastair · #12 05-20-2013, 05:08 PM

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?

petecooke · #13 05-20-2013, 05:17 PM

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

vstech · #14 05-21-2013, 10:41 AM

Quote:

Originally Posted by petecooke

**********************************************************************************
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.
************************************************************************************

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

My information in that old post was concerning 134 and POE oils... I'd just gotten some training in the field and the supco TXV manufacturer was adamant about the procedure for treating systems.
basically, the POE (Poly Oil Ester) has an EXTREME affinity for water, and any water collected will ONLY come out when the desiccant in the drier chemically removes it. pouring the oil into a dryer would draw moisture directly into the mix and drastically reduce the capacity of the desiccant.
for R12 and Mineral oil it's fine to pour 2 or 3 oz into the dryer, and 2 into the condenser inlet, and 2 into the compressor, and 2 into the suction line... just be sure to evacuate the system completely, it'll all make it's way throughout the system.

the best way to add oil to a system is put the dribble of oil into the compressor, then trickle oil into the other sections of the system, until the correct TOTAL volume of oil is in the system. DO NOT OVER FILL WITH OIL

petecooke · #15 05-22-2013, 09:37 AM

Thanks for the info. I followed dieselgiant's procedure a couple of years ago and used bg-frigi quiet. The system was evacuated and opened because the compressor needed to be removed due to an allen bolt being stripped while removing a bad vacuum pump.

The system was blowing cold and ran great. Now, I've been reading that BG-frigi quiet shouldn't be used or only 2oz used in the system. I wasn't planning on flushing the system or replacing the expansion valve since the system was working perfectly.

I plan on removing the compressor and draining it completely. Then replacing the r/d. Then add 8oz of mineral oil, pressurize with nitrogen and pull a vacuum.

There may be a little bit of the BG- frgi quiet still in the system but, since others use 2oz as an additive, I'm not sure it matter if the system isn't flush and it might help.

Would you flush the system?

Thanks.

pete