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Think I will keep the MGR R-12 for now but the compressor came with PAG.

1) Do I just drain or do I need to flush the compressor

2) Am seeing dual pupose oils like FJC Inc. 2445 DyEstercool A/C Refrigerant Oil and Dye are these any good ? System is dry now.

3) Normal system uses 8 oz of oil but the lines here are 20 feet long and it is dual air. Is more lubricant needed or is all in compressor and dryer ?

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Guest Richard D

Padgett, I drained the pag oil that came in my compressor, and since I used the same FJC Ester-cool oil you are using (without the dye) and it is compatible with PAG, mineral, pariffin, and just about any refrigerant oil I did not flush the new compressor. I did blow out the system with dry air before I evacuated it for a little over two hours. As far as amount of oil, the Reatta also uses 8 ounces, I put about three ounces in the compressor, and the rest in the acumulator and the high side to spread the oil through the system. I did turn the compressor by hand a few turns to be sure it was not hydro-locked and system has been fine. With your twenty foot lines you might want to add an extra ounce or two, I will ask a friend who is a marine A/C tech.


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Guest Mc_Reatta

You should flush the PAG oil out of the compressor not just drain, it as it will react negatively with the R 12 you plan to use.

The ESTER oil is a good choice as you can then convert to R 134 down the line and not have to flush all the oil out of the system like you would if you use mineral oil. Hopefully you won't have to flush for other reasons. ESTER is compatible with R 12 and R 134 so you can leave some behind although you will want to add PAG oil of the proper viscosity for your next compressor when you do switch over to R134. PAG is considered a better lubricant than ESTER, but not as good as mineral oil.

You will need to add at least 11 ozs of oil vs. the usual 8 due to the second evaporator in the dual system. Normally none is added for the lines in a standard system, but 20' long hoses is extreme. Wouldn't be surprised if and additional oz or 2 isn't called for especially if they have a lot of bends along their runs.

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Guest Mc_Reatta

Yes mineral oil is best but can only be used with R 12. Since some chlorine can be dissolved in it and carry over and react with PAG oil, ESTER oil has advantages easing the conversion to R 134 down the road. Flushing such a large system is not easy, so putting mineral oil in now will leave a big job later if you ever want to convert at some point.

POE vs. PAG Review

Polyol Ester (POE) oils are no longer the superior performer when it comes to compressor protection. Initial FALEX testing showed di-capped PAG to have a 66% advantage in wear protection over POE and ordinary PAG oils.

Di-capped PAG oils, or as it’s known in the biz ‘double end capped PAG oils,’ are patented and more compatible with future refrigerants like CO2, than conventional PAG oils. Di-capped is a chemical term relating to the process when a PAG molecule is altered by a reaction and the end result is a less hygroscopic (water absorbing) molecule.

PAG is a better lubricant than Ester (although not as good as mineral

oil, but mineral oil doesn't work with R-134a.). Plain PAG, however, is

highly reactive in the presence of chlorine (residue from R-12) and will

turn into brown goo. There are stabilized PAG oils on the market

("double-end-capped" PAG) that are supposed to be stable in the presence

of chlorine, but I question just how stable they are in the long run.

Will they start breaking down after 3 years? 5 years?. PAG oil also

absorbs water as readily as brake fluidgrey_loader.gif

, and shouldn't be used if stored

in an opened container for any length of time. Buy only enough for your

immediate needs.

Ester (aka POE) is less reactive and in fact can be used in straight

R-12 systems. But of the 3 available oils (PAG, POE, and mineral) it is

the poorest lubricant. But, since mediocre oil is better than oil that

has been turned to brown goo by chlorine, POE is usually used in R-12

retrofits. It absorbs water also, but to a lesser degree than PAG.

From Motor Magazine:

PAG Oil Is the Choice. All OE systems

now carry recommendations for

PAG oil (polyalkylene glycol), not the

polyol ester oils that had some limited

approvals for retrofit. Research has

shown that PAGs do a far better job and

substantially increase durability in R-

134a systems. All your suppliers are carrying

PAGs, and that’s what you should

be using in an OE R-134a system to

maintain the compressor warranty.

Viscosity Is Critical. But it goes beyond

just the type of PAG used. OEMs

also have found that the viscosity of the

oil is almost as critical. Some compressors

need a lightweight oil so it can flow

into some difficult-to-lube areas. Some

need a high-viscosity type to maintain

the lubricating film for quiet operation

and durability. And some need a midviscosity

oil. You can buy PAG oils in all specified viscosities, and you should install

what’s specified.

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