Refrigeration Oil - '75 R12 System

[Tommy F.]

During the rebuild of the '75, the entire refrigeration circuit has been purged....Now time to recharge the compressor with the initial oil charge, but I'm a little confused on which oil to use....I'll be using R12, but am having trouble finding the original oils at any auto parts site or store. I see plenty of synthetic alternatives, or I can buy a gallon of 525 sus oil from an HVAC supplier....Anyone got some advice?

Thanks,

[Larry M.]

Re: Refrigeration Oil - '75 R12 System

Tommy:

You don't need a gallon, a quart will be more than enough. Go to your nearest NAPA and request Item #TEM209500. It is a quart of 525 viscosity mineral oil for R12 systems.

Another option is Advance or O'Reillys. Request Interdynamics #R0-27. Also a quart of R12 mineral oil.

Your total system oil capacity should be around 12-15 ounces. This is for a clean system and includes the compressor. Check your Chevrolet Service manual for the exact charge.

Larry

[Michael G.]

Re: Refrigeration Oil - '75 R12 System

Larry,
How clean does the system need to be? Will those oils work if the system still has some residual original oil. I'm getting ready for a recharge too and have't done a thorough flushing of the system. Any advice would be appreciated. Mike

[Larry M.]

Re: Refrigeration Oil - '75 R12 System

Mike:

The oils I recommended to Tommy are the same/identical to the original refrigeration oil installed by the factory. There should not be any compatibility issues, unless somewhere along the line someone used a PAG or Ester Oil (unlikely unless done in conjunction with a change to R-134a).

I would make sure the compressor is drained and then add back the required amount of oil (7-10 ounces depending on compressor....check your Shop Manual). I would use low pressure (30 psig) DRY air or nitrogen (preferred) and blow out the condenser and evaporator. Then clean/replace the inlet screen to the expansion valve, and replace the receiver dryer. Add the remaining oil charge to the receiver dryer or the condenser, and button everything up. Pressure test with some nitrogen (or R12....which is not EPA endorsed), vent, pull a deep vacuum for a few hours or overnight, and then charge with R12.

Measure your charge if possible (scale or number of cans).

Check again for any leaks, and then start the car/AC system and add the remaining R12.

Larry

[Jay G.]

Re: Refrigeration Oil - '75 R12 System

Mike:

The oils I recommended to Tommy are the same/identical to the original refrigeration oil installed by the factory. There should not be any compatibility issues, unless somewhere along the line someone used a PAG or Ester Oil (unlikely unless done in conjunction with a change to R-134a).

Larry,

I am in the process of completely rebuilding my system and will be using R-12 to recharge but am considering going with ester oil so that in the event I wanted to move to R134 there wouldn't be any issues. I have done some research on the subject but haven't really seen any answers that say this is a good or bad idea. Do you have any thoughts on using ester in an R-12 system?

Regards,

Jay

[Larry M.]

Re: Refrigeration Oil - '75 R12 System

Jay:

You are correct. Information over the past few years has indicated that R12 mineral oil and POE oil (ester) are compatible, and that POE can be used in R12 systems. Based on this, you should be okay to use in your system.

I personally don't like mixing oils, so I recommended to Mike at least blowing out the old oil from the hoses and AC components before adding new.

With the cost of R12 coming down (you can buy for around $15-20 a pound on E-bay), it seems to me that the possibility/need of converting to 134a down the road is low. Therefore just use R12 and the original 525 viscosity mineral oil. But your point about using POE oil is valid, and may be the best choice for your situation. I just don't have experience with this combination.

Larry

[Tommy F.]

Re: Refrigeration Oil - '75 R12 System

Thanks Larry...I actually went to NAPA today, and the girl behind the counter looked at me like I was from Mars....Also checked the sites for O'Reilly, Advanced, and Auto Zone....with no luck.

I'll bring the numbers with me tomorrow.

As always, I appreciate the advice.

[Jay G.]

Re: Refrigeration Oil - '75 R12 System

Jay:

You are correct. Information over the past few years has indicated that R12 mineral oil and POE oil (ester) are compatible, and that POE can be used in R12 systems. Based on this, you should be okay to use in your system.
...
Larry

Larry,

Thanks for your thoughts.

Jay

[Larry M.]

Re: Refrigeration Oil - '75 R12 System

Tommy:

I just bought some less than 6 months ago, so I know it's still out there......even in Louisiana.

It's also on their (NAPA and O'Reilly) websites. Check it out for specs and details. Use the Item#s I provided.

Larry

[Michael G.]

Re: Refrigeration Oil - '75 R12 System

Larry, Thank you . I'm a little weak in the AC department and appreciate your directions. Thanks again, Mike

[Tom L.]

Re: Refrigeration Oil - '75 R12 System

I'm in the Refrigeration and A/C buisness, so here's a pep talk.

This is a quote from an article on Dupont's (You know, the chemical company) "Beginning January 1, 2011, HFC-134a will be phased out for air conditioning systems for new vehicle models. By January 1, 2017, it will be banned for all new vehicles."

The automotive industry is the #1 user of 134a and as it turns out it is ont the "environmentally friendly dream refrigerant" that it was thought to be back in the 80's when first developed so it will eventually go the way of our old friend R-12. This does not mean that 134a is going away any time soon but... Production will decline as a result and the cost increase will be painful.

As an example, R-22, the refrigerant used in our home A/C units IS currently being phased out. As of 2009, producction has been cut 25%. In anticipation of this, the cost of R-22 more than doubled in 2008. That trend will continue as all production ends in about 5 years.

So, what I'm saying is there is no secure replacement for any refrigerant. If you have a supply of R-12, use it and the mineral oil. you'll have to change refrigerant and probably oil in the future anyway!!

good luck!!!

[Oliver B.]

Re: Refrigeration Oil - '75 R12 System

When I had my AC refilled some 5 years ago (over here in Germany where there is no R12 to be sold or purchased since a couple of years ago!) I got R413 filled in.
This did not require the gaskets to be changed/refitted like for R134A, which tend to bleed the R134A over time...

Never heard about using R413 before, but have no problems (aside from the feeling that the R12 performed a better cooling) until now...

[Tom L.]

http://refrigerants.dupont.com/Suva/en_US/products/isceon49.html

[Oliver B.]

Re: Refrigeration Oil - '75 R12 System

Interesting! ...Hope that I will not get any losses in future - still I am happy that I was able to avoid changing all the gaskets when refilling. Then "they say" that the AC needs to be refilled every once in a while anyway...