Mixing AC compressor oils - how bad? - PeachParts Mercedes-Benz Forum

Maxbumpo · #1 08-11-2019, 01:14 PM

Yesterday I finished up re-seal of the AC compressor in my '87 124.193 (shaft seal had failed, sudden discharge of system).

The system has had PAG-46 compressor oil in it, but I made a mistake and re-filled the compressor with mineral oil. I put in 50 CC of mineral oil, and then proceeded to put in two cans of r134 (had planned to use EnviroSafe propane / butane blend but realized too late the I didn't have enough on the shelf).

So, what to do? Flush the system of all oil, and start over, or ???

Does the PAG oil get carried around the system by the refrigerant, and the mineral oil mostly stay in the compressor? If this is true, I'm wondering if I can take it to an AC place and have them evacuate and pull all or most of the PAG oil with that operation, and then I can switch over to mineral oil and not have to flush all the components.

tangofox007 · #2 08-11-2019, 01:58 PM

Quote:

Originally Posted by Maxbumpo

I'm wondering if I can take it to an AC place and have them evacuate and pull all or most of the PAG oil with that operation...

Don't expect evacuation to remove more than a trace of oil.

ah-kay · #3 08-11-2019, 03:11 PM

If it works then leave it alone. You may be able to bridge the 2 non compatible oil by adding a bit
ester oil. Google it for more info.

Maxbumpo · #4 08-11-2019, 03:50 PM

Reading the MB service bulletin for converting from r12 to r134, they say to run the AC system on high for ten minutes, shut off and evacuate r12 with recovery machine for 45 minutes, re-fill with r12, repeat process of run and evacuate / recover. I suspect this process removes most of the original mineral oil that was used. Once this is complete, add proper amount of PAG oil and refrigerant.

Maxbumpo · #5 08-11-2019, 03:51 PM

It looks like the present charge of r134 will not move the mineral oil around, but will move the PAG-46 oil around.

What a mess.

Frank Reiner · #6 08-11-2019, 04:02 PM

Mb:

In the event that you have not run the compressor, consider removing the compressor, dumping the mineral oil that you put in, rinsing with a bit of PAG, dumping that, and then refilling with PAG.

Diseasel300 · #7 08-11-2019, 04:31 PM

Mineral oil will not circulate with HFC refrigerants, basically the compressor will pump it into the lines where it will stay, not returning to the compressor. Not only will it oil-log the coils, but you reduce the amount of oil in the compressor sump potentially leading to seizure of the compressor.

Evacuate and flush the system, drain the compressor, and start over. If you want a universal oil use PAO or POE oil. Both will circulate with HFC, CFC, or HC refrigerants. PAO has the added benefit that it is not hygroscopic (won't absorb moisture from the air).

Maxbumpo · #8 08-11-2019, 05:53 PM

At this point my plan is to remove / drain / flush the compressor and the condenser and the lines from the compressor to condenser and from condenser to drier.

According to Enviro-Safe FAQ, their refrigerant is compatible with all compressor oils. Denso recommends the PAG-46 oil with this compressor, which is what I have been using and have not suffered a compressor failure after a couple years of use.

Diseasel300 · #9 08-11-2019, 05:59 PM

Be aware that Enviro-Safe is nothing more than propane with pine scent added.

vstech · #10 08-12-2019, 07:15 AM

Quote:

Originally Posted by Diseasel300

Be aware that Enviro-Safe is nothing more than propane with pine scent added.

My understanding is, ES is a blend of butane and propane with other chemicals for a good R12 alternative.

R290 for home R22 and some small portable AC units use pure propane...

97 SL320 · #11 08-12-2019, 12:58 PM

Quote:

Originally Posted by vstech

My understanding is, ES is a blend of butane and propane with other chemicals for a good R12 alternative.

R290 for home R22 and some small portable AC units use pure propane...

Last I checked , R290 / propane isn't legal for a building AC retrofit and is limited to some small amount for new builds.

ES has a university ( student ) paper they use to show what they are selling is " safe ". https://www.es-refrigerants.com/resources/docs/PERFORMANCE%20AND%20SAFETY%20OF%20LPG%20REFRIGERANTS.pdf

It is mostly junk science as it uses the outright cost of R12 to offset the cost of insurance ( Page 15 ) and claims that an explosion in an occupied car will:

Quote:

Page 12

A complete and instantaneous rupture of the liquid line just upstream of the expansion valve could release a white cloud of perhaps 300g of LPG refrigerant into the passenger compartment. Opening a window would create a safe situation in seconds. If all occupants ignored the cloud and one lit a match, the windows would blow off the car in a second. Replacing the glass may cost $1000 and LPG explosion accidents with domestic appliances show occupants’ exposed skin would be red and sting for a few days. The glass flies away from the occupants and the resulting in-rush of cool fresh air limits burns and importantly prevents asphyxiation. The authors and their students have made measurements to estimate the probability of this accident.

A real test
https://www.youtube.com/watch?v=FO47SzxJmV0

Hydrocarbon refrigerant flammability test archive footage
on the channel VASA
~~~

All we need to do is substitute professor Honeydew as the presenter and his long-suffering assistant Beaker as the guy in the car. Or maybe Phil from " Better off Ted " in the car.

https://www.youtube.com/watch?v=DjtowzVzl_4

A video of a hydrocarbon refrigerant demonstration which wen
on the channel LOPMAS

Maxbumpo · #12 08-12-2019, 04:48 PM

All ya'll Enviro-Safe haters can just keep on hating, and put what you like in your car. I'll put what I like in mine.

Fair?

The original post and question are about the proper oil to use, and I'm satisfied that the answer is PAG-46. I'm probably going to splurge and get the Denso stuff for about $20 for 500 ml, as it is double-capped and much less hygroscopic than FLAPS PAG-46.

Maxbumpo · #13 08-12-2019, 05:29 PM

Just found another source of hydrocarbon (flammable) auto refrigerant, FrostyCool:

Wholesale Refrigerant - Cheap R22 Freon, R22a, R410a, R12a, R134a Replacement

Looks like they are about $10 per case cheaper than Enviro-Safe.

97 SL320 · #14 08-12-2019, 06:18 PM

Quote:

Originally Posted by Maxbumpo

All ya'll Enviro-Safe haters can just keep on hating, and put what you like in your car. I'll put what I like in mine. Fair?

So you are saying that if ES caught fire in a car you were driving and you were so badly burned you could not work, you would not sue someone? How about your passengers? Do they consent to riding in a car with an unsafe refrigerant after you have informed them?

post 25
https://hvac-talk.com/vbb/showthread.php?1584811-Enviro-Safe/page2

Enviro-Safe provided a good real life example of what happens when ES-22a and like accidentally ignites. Last year, Enviro-Safe second generation refrigerant gas thingy caught fire in its own re-bottling plant and caused a serious industrial accident. Four injured. Two life flighted to hospital. It blew off the building's roof and a portion of the wall and it had to be demolished. Oh and a couple months later, EPA gave them a violation notice for selling illegal refrigerants.

Diseasel300 · #15 08-12-2019, 08:22 PM

Quote:

Originally Posted by Maxbumpo

All ya'll Enviro-Safe haters can just keep on hating, and put what you like in your car. I'll put what I like in mine.

I wasn't hatin' on it, just making sure you knew. Some people think it's some sort of magic potion (it isn't). I ran it for a while in my SDL and it worked fine when moving, didn't work well for me in low humidity high temp low speed driving though. Ironically 134a works better for me in my climate so I've stuck with it.