What viscosity PAG on my 5/96 build 740iL? finding conflicting info: 46 or 100.

[cyclops2]

Taking car to guys home based shop to charge the a/c. I want to come with all facts to verify prior.

I found that R134a capacity is: 1210 +/- 25 grams.

I have found that the oil capacity is about 6 ounces. But just can't confirm which 46 or 100.

I understand that only a couple ounces are needed since only the drier was replaced.

Background: a/c not used for 5 years during build project (car on blocks). Had no problem historically and working fine when vehicle project started. Had to remove a/c line from drier to firewall to access fuel lines on 6/2015. Didn't reinstall the line and replace drier until 10/2016 (but not serviced). a/c service/recharge is scheduled for today (12/2/2017). I am hoping this drier will be ok even though the system not charged but at least contained in the a/c plumbing (otherwise, I realize anytime the a/c system is open the drier should be replaced AND the system recharged within 24 hours).

Any additional thoughts appreciated. a/c tech was referred to me by Danny (forum/BMW enthusiast) so I am confident in this guy, but I always like to know the basics to be certain.

Thanks.
Dan

[racer2086]

I think I remember doing PAG 100 in my 98 based on my research. I remember it was the harder of the 3 to find. The auto parts store always had PAG 46 and PAG 150 but didn't have much PAG 100.

My biggest concern for your system is the very hygroscopic nature of the PAG oil. The length of time you had the system opened means that the remaining oil is probably acidified from absorption of moisture in the air. Some of the newer oils are "double end-capped" to reduce the hygroscopic tendency, but for that length of time, I'm not sure it matters. Ask the A/C guy. He may say it's fine. Otherwise you'll need a flush to get that oil out.

I do not know about the drier sitting for 2 months absorbing whatever moisture were in the lines. I'd probably replace it right before the evac and charge, but I do not know if that is required.

[cyclops2]

Well attempt at a/c recharge ended with leaks found in a couple lines. So I need to order orings (will replace all) and I'll order a drier at that time as well.

I am also going to replace the Shrader valves/caps. I have flush kit so am now thinking about doing this right. Should be straight forward to flush all... except would require the removal of compressor to properly drain it.....ugh...

just want to be done and be driving... lol.. but don't want to start cutting corners now...

I've continued to research the PAG46 vs PAG100 and I find conflicting info all over the place. I'll call BMW service department tomorrow.


Tuesday is alignment... step-by-step still moving along.

[racer2086]

Good luck. I'm 80-90% sure PAG 100. At least that's what I used. Good luck. Getting there

[atakordie]

I used PAG46 on my 2001 750, but I was going off of what the spec was on the compressor itself.

[acspecialists]

Factory would be PAG 100, it is rare. If the system has been open that long you need to get all of the old oil out. The worst thing you can do to an a/c system is let it sit. New oil, Dryer and orings. If you do flush it (I would not recommend it) make sure you evacuate it for at least and hour. You need plenty of time for the water and solvent to flash in a vacuum and get pumped out.

[cyclops2]

[QUOTE=acspecialists;29902554]Factory would be PAG 100, it is rare. If the system has been open that long you need to get all of the old oil out. The worst thing you can do to an a/c system is let it sit. New oil, Dryer and orings. If you do flush it (I would not recommend it) make sure you evacuate it for at least and hour. You need plenty of time for the water and solvent to flash in a vacuum and get pumped out.[/QUOT

Thanks everyone!

Thanks AC, a few questions.

So I can get this PAG100 at Autozone; it is 8 ounces which includes 1 ounce of lubricant enhancer.



Link: https://www.autozone.com/a-c-chargin...ors/424624_0_0

I understand the PAG volume spec for the 740s is 5.1 to 7.1 ounces. So should I use 7 ounces of this (assuming I can remove all old oil)? For that matter can I use this with the enhancer? If so, how distributed throughout the system?

[racer2086]

I generally don't like putting additives in my AC system. There should be a few ounces in the compressor, couple ounces in the dryer, the remaining ounces throughout the lines of the system.

[cyclops2]

Thanks Racer,

I can get this DEC (double end capped) PAG100 locally with no additives whatsoever.


http://www.ackits.com/case-6-8-oz-ul...486?search=pag


So I understand no enhancer, but what about dye? I as going to add some UV dye, but should I just rely on the vacuum testing of system initially rather than adding UV to recharge.

[Reflex]

If your compressor is manufactured by Bosch/Behr, Seiko Seiki, Seltech, Tama or Sanden, you need the PAG-Oil 100. If it’s manufactured by AC Delco, you need the PAG-Oil 150. If it’s manufactured by Behr, Denso, York or Zexel, you need the PAG-Oil 46.

You also have the option of PAO-Oil 68 AA1. This one is a synthetic oil that is compatible with all types of automotive compressor oils and refrigerants.

[cyclops2]

If your compressor is manufactured by Bosch/Behr, Seiko Seiki, Seltech, Tama or Sanden, you need the PAG-Oil 100. If it’s manufactured by AC Delco, you need the PAG-Oil 150. If it’s manufactured by Behr, Denso, York or Zexel, you need the PAG-Oil 46.

You also have the option of PAO-Oil 68 AA1. This one is a synthetic oil that is compatible with all types of automotive compressor oils and refrigerants.

Good post, thanks. So the viscosity is defined by the compressor mfg and not the vehicle manufacturer (in other words, system influence)? I have seen that the range of vehicles that my build year is (5/96) they used either Denso or Seiko Seiki.........but I am not sure. I have seen that there are many models of Denso and they seemed to specify between PAG46 and PAG100.

I have also read that PAG100 is recommended when no spec if provided or known and that it is a universal viscosity... but I don't know if that is true.. just something I read on the Internet....lol


At this point, I am leaning toward PAG100 without any additives. However, I am looking into pulling the compressor for a proper drain and refill, so at that time, I'll determine what model/maker compressor I have.


So how to handle dye? don't use it unless I have to troubleshoot a problem? seems to me it shouldn't necessary if it holds a vacuum for a long time. I am going to pull a vac for an hour and then leave under vacuum over night.

For me, this is a project to do in a week or so.

I need to better understand flushing, acspecialist said he didn't recommend it. But how else do I flush/clean out a system that has been exposed for years?

Thanks all.

[racer2086]

You can add a couple ounces of dye if you want. You can buy that separately. Yes, if the system holds a vacuum then you know there is no leak. That is the way to tell when you have the system empty.

I haven't flushed a system, but from what I've read, there is a specific flush fluid to use. I'm not sure why that would be bad to flush out the lines and evaporator, except you just need to make sure all the flush fluid and any moisture is completely boiled out of the system by pulling a vacuum.

[cyclops2]

You can add a couple ounces of dye if you want. You can buy that separately. Yes, if the system holds a vacuum then you know there is no leak. That is the way to tell when you have the system empty.

I haven't flushed a system, but from what I've read, there is a specific flush fluid to use. I'm not sure why that would be bad to flush out the lines and evaporator, except you just need to make sure all the flush fluid and any moisture is completely boiled out of the system by pulling a vacuum.

Thanks Racer,

I will pass on the dye. seems that is something I would consider later if a leak develops. But I am going to have the system under vac for overnight so there will be no leak.

So eventually I will get "pure" PAG (no additives) once I get at the compressor and check make and model - then I can determine 46 or 100.... since there is still some potential conflict in the answer.

Regarding the flush, I purchased a simple flush kit from an a/c shop so it is legit with proper chemicals - but I need to dig it out and post info here for feedback.

Seems I need to remove and drain the compressor and refill. replace the drier. replace all orings. I am going to reassemble with Nylog as well.

But to do the system properly it will require flushing. Just not sure that is what I need to do.

OK, will keep this thread updated.

[racer2086]

Just wanted to post back here to clear things up for future searches (I use them! ). I just started researching this again, since I'm working on my dad's E46 M3 A/C. I wanted to know if that car was the same oil as the E39 and E38, because I didn't want to use my same equipment and contaminate things if they were different.

It turns out after reading on newtis.info that all of these cars used Denso compressors. And as poster Reflex stated above Denso compressors use PAG 46 oil. That is cross confirmed with newtis in that the oil specification is Denso ND8, which is low viscosity, which equates to PAG 46. Newtis has two part numbers for the oil: 81342147762 (500ml can of ND8 = PAG46) or 81229407724 (250ml can).

They also have a chart on there that specifies what is acceptable loss of refrigerant per year and if it is more than that, how much oil to add back to make up for oil loss. Good info!

So, to summarize, the oil is dependent on your compressor. But it appears that E38, E39, E46 cars using Denso compressors require PAG 46 oil!

[nmlss2006]

Bringing this back up again: @racer2086, according to what you found therefore E38s use PAG 46, because they use DENSO compressors?

In another thread, a BMW TSB from Timm seemed to indicate that the FL cars used Seiki compressors, which would then necessitate PAG 100. BUT, in the same thread, the OP said the compressor tech told him it's a Denso compressor which uses DENSO ND-8, equivalent to PAG 46.

I am quite confused.

[racer2086]

It is very confusing, because it is based on the compressor in your car. You should be able to find a metal label plate on the compressor to find out which one you have. It is likely buried under ages of greasy sludge from leaking valve covers and upper timing covers.

Use Newtis for info, though. It is a great source and the final say on what to use, because it is the BMW service manual. Other option is to check realoem.

It's been so long, I don't remember what I used. It sounds like I used 100 from my earlier posts. What I can tell you is that whatever I used, it's still running great 3 years later.

[CPHES]

But that is all there is to it. Find the label on the compressor installed, and get the oil for it.

[nmlss2006]

OK, thank you folks. I'll go hunting. Perhaps it'll stop being 95 degrees here and it'll be a little less bad.

r2086, I did look in newtis and the info there was not as clear as I hoped - perhaps I was looking in the wrong place? I'll look some more.

[chemmech]

you mentioned flushing out the system... I did a few retrofits from r12 to r134a in the past, the main reason was to get the older type oil out of as much of the system as possible, I can figure if your system has been opened for a long time the oil may have absorbed water? a new dryer as well as a flush would be recommended, I would drain the compressor oil (not flush it though) and flush the lines, evaporator and condenser to try to remove as much of the old oil as I could this is just what I would do if it was the system in my car though and really bad oil was in it the add the oil to the components as specified etc. install etc. seems you have a bunch of correct info in the above post so, since the lines will need to get disconnected I would recommend getting new proper o-rings needed to reseal the system also (they are Highly Saturated Nitrile Rubber o rings(HNBR) the green color o-rings ( I guess, not viton that's for hydraulics etc.))... there are many flush systems; some are all self contained aerosol cans with hoses and others are a type of canister you have to fill and use a compressor to pressurize, the type I used was the one used with the compressor to pressurize it after adding the flush real expensive and after draining the fluid it just evaporated and then was ready for installation..... if it's not that bad just replace the stuff pull a vacuum on the system and just make sure all the moisture is out.. if it won't hold a vacuum after resealing and letting the system sit for awhile after pulling a vacuum then you may have an air leak or way too much moisture in the oil etc. degassing etc. back out of the oil from dehydration process etc. ...... you may need a micron gauge to do the moisture check etc. .....

is there stuff that got into the lines accidentally drug on the ground etc. like gravel a coke can a c... etc. then I would flush at least those parts or just wipe them off real good....

[nmlss2006]

And I am bringing this back up further to confirm: so I pulled the refrigerant, pulled a vacuum (with a crappy ebay pump, but that's relatively relevant since there was R134a in the system from the factory still) and put in 700g of 'fresh' R134a, Dupont/Chemours original (yes, I am aware that the factory spec is 680+/-10).
Not only did my vent temps go to the low 40s at idle in a ~90F garage, compressor noise is entirely gone without even adding oil.
racer2086 had reported on this previously and he was entirely correct. Fill the system with coolant first, THEN add oil if necessary.
Now I get to figure out how long this will last, of course. The charge that had mostly depleted itself - I pulled less than 300g of coolant out of the system with the Mastercool recovery machine - was, to the best of my knowledge, factory from 06/2000 (!!)
I'll report back.

[Sanderss69]

I came across this site when I was needing to recharge my ac and was not sure how much
https://www.techchoiceparts.com/refr...capacities/bmw this should tell you all you need to know for factory specs


Sent from my iPhone using Tapatalk

[nmlss2006]

Be advised, several of the specs on that site are NOT correct. The 99+ E38 does NOT take 55 oz of R134a.