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Synthetic refrigerant oil versus Pag or mineral oil

Started by Cadman-iac, June 03, 2023, 11:50:50 PM

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Cadman-iac

  I have a question for the A/C experts here. I have been through an A/C training program years ago, and my teacher had suggested that a synthetic pag oil would work better in a conversion from an R-12 system.
I have done several conversions to R134A on older vehicles, and initially I used the regular pag oil that was given to me when I bought the compressor.
Twice I've had the compressor fail within 6 months. After replacing them the second time, I used a synthetic pag oil, and both of them are still working great years later. (These were both R4 compressors).
I've since only used the synthetic oil whenever I replace a compressor and have not had any problems.
I was also told that the synthetic oil would not react the same as the regular pag oil would if it were to mix with any residual mineral oil in the system. How true is this? I'd like to know, but my experience seems to bear this out.
I have even tried a little experiment with the oils by mixing a small amount of each, pag and synthetic, and mineral and synthetic,  in a clear container, to see just how much they would mix, or not mix. In both cases, you could see a distinct line between the two oils. Even after thoroughly mixing them, after leaving them sit for an hour, that separation could be clearly seen.
Has anyone else used this synthetic oil, and what do you think of it? What has your experience been with it?
Here's a picture of what I'm referring to.
When I first bought some of it, it was on the shelf at my local independent parts store. They were subsequently bought out by the competition, and it's no longer stocked, and I had to order the next bottle of it online.
Another question, is there a synthetic oil available that would replace the mineral oil in an R-12 system?  If so, what issues has anyone had with it if any?
The reason why I'm asking is that I don't want to have any problems with my 56 once I have it charged with R-12. I'll be using an A6 compressor because it fits the 472 engine, and I have never had any problems with the A6, other than the pulley bearing and the coil.
Do you think a synthetic replacement for mineral oil is necessary or helpful, or a waste of time and money?
Thanks in advance for your input.

Rick
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

TJ Hopland

I'm for sure no expert, just a guy that got tired of being screwed over by shops that seemed to know less than I did and being hot all the time.  Sounds like I had a pretty similar experience as you with apparently doing everything right and using the recommended by 'they' PAG oil and destroying new compressors.

On one of my trips to the store to buy yet another compressor I got a different counter guy that recommended ester 100 oil.  Like you most of mine are converted systems from the 80's and 90's from the big 3 and since I went to the ester I have had zero issues with any of them.  Its actually been so long since I have had to mess with any of my cars AC's I don't even remember a lot of the details like if I used the ester on my 98 also,  I think I did.  That one did loose its charge but when I was taking the engine out that blew up I found a hose fitting that was just hand tight so that was likely what caused the leak.     
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Cadman-iac

Thanks TJ,
Yeah, I'm not convinced that the recommended oil for an R134A system is the best choice. Until someone can prove to me that it is, I'm going to continue with this synthetic oil.
I appreciate your input on this. Sounds like you got the same pitch as me with the same results. Good luck on your future A/C endeavors.

Rick
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

"Cadillac Kid" Greg Surfas 15364

Let's get back to basics. When rotating machinery such as AC compressors are designed the lubricant for their parts is selected based upon it fluid (viscosity, dynamic shear, temperature tolerances, chemical compatibility with the materials involved in the machinery, etc.). The bearings selected for the machinery are selected based upon their compatibility with the lubricant selected and then the clearances and flow quantities are determined and incorporated into the machines design.Changing Lubricants AND the refrigerant used in a compressor from those it was designed for and all bets are off.
As far as oil compatibilities (with each other) you need to go directly to the manufacturer's information or their engineering facilities.
Anecdotal information (I tried "this" and it worked) is typically a shot in the dark.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

TJ Hopland

When I was in the thick of it I remember trying to find out what the official lubricant was for a new compressor and was unable to find out.  My parts guy also asked when he was trying to help me out and force them to warranty a compressor.  They even went as far as saying I wasn't using the right oil but could not tell me what the right or even wrong oil was. They finally gave in and warrantied the compressor but never came up with what oil it was supposed to use.  I think it was when I picked up the warranty replacement was when that counter guy told me to do the ester. 

 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

"Cadillac Kid" Greg Surfas 15364

The "right" lubricant is the one the compressor was designed to use. All others are just a shot in the dark.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Seville Life

Well I'm with Greg.

The RIGHT oil is 525 mineral oil. Obviously it cannot be used with 134a.

It was said right at the start of this piece, 134a is just not a great choice for conversion.

The answer (UK & Europe) I believe is RS24. It is a direct drop-in gas. Weirdly it's largely unknown.

Paul Bedford

"Cadillac Kid" Greg Surfas 15364

This is (was) an acceptable and effective replacement for R-12 in automotive air conditionin, Just like R-414b WAS. 414b was a blend with R-22 in its mix and when the price of R-22 went through the roof, they quit manufacturing it.

What is r24 refrigerant?
RS-24 is a non flammable blend of HFC 134a, HFC 125, butane and isopentane

R-134a has become "persona non grata" in Europe, so RRS-24 will not be far behind.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Seville Life

134a is not in any way persona non grata in Britain or Europe. There is much discussion by the corrupt and incompetent EU people that it will/might/possibly be stopped?

They all know, like two-pack paint, that entire sections of automotive would disappear if they did that.

It's the norm for companies that re-gas a/c on cars? New cars have it fitted so dealers re-gas

I know many with Cadillac and Rolls who are, sadly, still wasting their time with 134a conversions.

RS24 is available (expensive) but it is still available.
Paul Bedford

Cadman-iac

  Would that RS24 be available here in the US, or is it just in Europe?
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

Cadman-iac

#10
  I realize that the "environment" is different inside of an A/C system than say in the engine itself, but synthetic oils are used every day in all types of engines without detrimental side effects, and it's almost always better than the conventional oils by far.
Why would this not be true for the A/C system as well, given that the synthetic pag oil was designed for use with R134a and in an A/C system?
I'm not an engineer, nor do I claim any special knowledge of oils or compressors, but my own experience has proven, at least to me, that this synthetic pag oil is far superior to the "suggested" oil specifically for R134a.
And given the reputation of the R4 compressors specifically, I'd say that it's doing a great job keeping the compressors from grenading. I'm running 2 R4 compressors, one in a 1988 Suburban, the other in a 1990 Suburban, and I live in Arizona, and run both very hard at interstate speeds, 75+, and for the last 5 years, not a whimper from either one.
I have rebuilt a few A6 compressors, (more than just a reseal), and I'm fairly certain that the synthetic pag oil will work just fine in them as well if converting to the R134a. The A6 is much easier to rebuild than an R4 is, and I've done one of those as well. I had to make some special tools to get the pistons out and back in, and to remove and reinstall the outer case, but the lack of any parts for them doomed this one from the start.
I mainly did this just to understand how it was designed and works, or in some cases, doesn't work. I did get an additional summer's usage out of it though.
I'm not going to use a synthetic oil in the A6 on my 56, because hopefully I'll have enough R12 to charge the system. I'm not wanting to convert it to R134a at all. I'd rather use propane than switch to R134a in this car, and 525 mineral oil is just fine for that.

I simply wanted to know if anyone has had any experience with this synthetic pag oil and what, if any, issues you've had.
My thanks to each of you for your comments thus far, it's definitely interesting to hear what you think.

Rick
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

"Cadillac Kid" Greg Surfas 15364

Richard,
Refrigeration lubricants lead a much more complex lift than just lubricating. They have to be capable of being entrained by refrigerant, tolerate drastic changes of temperature and velocity without loosing any of their required characteristics, have minimum moisture adsorption qualities, and have an infinite life time.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Cadman-iac

Yes, I know it's about as severe an environment as any oil would ever be subjected to.
I don't know what kinds of testing that this synthetic pag oil was put through, but I would imagine that in order to sell it for it's intended purpose, it would have had to go through the same processes as the regular pag oil would have had to.
I know I was skeptical about Mobil 1 when it first came out, but it proved itself to countless millions, and now is even recommended by Cadillac in their engines, or was when I was still working at the dealership.
Is it possible that this stuff actually does do everything that it's supposed to do?
There are additives that are used for A/C systems, like "Fridgi-quiet" that help lubricate and quiet a noisy compressor, and I've used it in the past with good results. I can't remember if it was synthetic or not, I believe it is, but I hadn't used it for R134a, just in an R-12 system in conjunction with the mineral oil, with no problem. (This was another product that my teacher had suggested to use with a compressor replacement.
I also don't know if there is a synthetic oil replacement for mineral oil to be used with R-12, but if not, at this point in time I doubt that anyone will be developing one. Too bad really.

But I'm relying on the expertise of the people who are designing and making the product to understand what this stuff goes through and hoping that they get it right.
I just know that I've converted 7 or 8 systems since I started using this synthetic pag oil, and so far there have been no problems with any of them, yet.
  Maybe I should not have asked for input on this, but I was curious to know if anyone else has had any experience with it.
I definitely do appreciate your input, and I thank you for taking the time to respond, and I think I understand your concerns.

Rick
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"