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Sat Jun 08, 2024 8:53 am

I am in the process of reconditioning the air conditioning system on my 1985 Westfalia. New hoses, parallel flow condenser, flushed out evaporator, new receiver dryer, new compressor. I live in Northwest Florida, so cold weather is not really an issue, so I thought I would use pag100 oil, as it is suppose to be better in warm weather. I wanted to replace the oil in my new compressor, hoping to put a better quality oil in it right from the get go, but I noticed it came with pag 46 oil. I was going to replace it with pag 100, but somewhere, someplace I think I read that one should stay with what the manufacturer recommends, which is pag 46? I've already put pag 100 in the evaporator and condensor as I was assembling the system, so I guess I could flush it out if I need to, but that would be a pain, especially as my evaporator is in the back in the headbanger cabinet.
So my question is: is it ok to continue with pag 100 and to refill the compressor with pag 100? Or would that be a mistake? A/C shops near me were divided, and I knew there are some sharp guys with A/C on here, so I thought I would ask you guys. Thanks!

Sat Jun 08, 2024 12:35 pm

If you want to be safe, I'd suggest flushing out the PAG 100 and using only the PAG 46. I don't think you'll find a compressor Mfg that will "approve" of using any viscosity or oil type other that what they've designed the specific compressor for.

If it were me, on my vehicle, I'd drain out and flush everything I could (ignoring the evap) and refill with PAG 46. The effect on overall viscosity would likely be fairly minimal, and the various viscosity PAGs are all miscible from what I've seen. But my rig won't likely be getting more than 50k on it before I cash in, so I'm not that concerned with maximum mileage before failure. YMMV

Sat Jun 08, 2024 12:41 pm

The compressor dictates the oil type /viscosity

Draining/replacing with same amount new compressor oil is best practice since oil can pick moisture and it's a good verification of oil volume so you can oil balance the system for the oil/refrigerant ratio the compressor and system is designed for

The best solution would be to replace the condenser (and RD receiver drier if ot had oil put in and if it hadn't it should stay factory sealed and put in lat right before vacuum) since these cannot be flushed and flush everything else with the incorrect oil and then refill appropriately.

So that being the best practice, let's look at what it might go like if you ran 100 or mix of 100/46....

If worse case the compressor fails miserably due to wrong oil - you're still flushing and replacing condenser and RD and possibly the TXV AND the compressor along with the refrigerant....
Plus you are then flushing all the hoses instead of just the evap.

..... So the difference in time/materials s the compressor $200?, TXV $50?, and refrigerant "$50 so like $3-400 and the hose flush.

If it was me, I'd make it right now and be done with it.

.....and very likely running with that you have it may last.

(Rolling dice emoji)

Sat Jun 08, 2024 1:51 pm

this is basically the 5/30 10/30 20/50 debate with engine oil

46 would be fine in a fresh system. I'd use 100 in a old(er) system

if the company wanted 46 in a new install, fine. but if that new install was 200k miles old, i'd toss in 100

use your judgement. mixing the 2 won't hurt a thing. you'll end up with pag 62 :lol:

https://www.teclub.com/shop/air-conditioning/a-c-lubricants/pag-compressor-oil-46-100-150/

Sat Jun 08, 2024 2:18 pm

skills@eurocarsplus wrote: 46 would be fine in a fresh system. I'd use 100 in a old(er) system

if the company wanted 46 in a new install, fine. but if that new install was 200k miles old, i'd toss in 100

Unless I missed something, this is a fresh install. All components are new.

As far as flushing the condenser, you may not be able to flush it sufficiently to eliminate an incompatible oil, but since you're using the same oil, just a different viscosity, flushing out to a negligible residual should be no problem, IMO.

Sat Jun 08, 2024 2:41 pm

khughes wrote:

Unless I missed something, this is a fresh install. All components are new..

that's what I'm saying. run the 46, anything that mixes may thicken it up a bit, like dumping 10/30 into a 5/30 engine...in the end, it won't amount to shit

if the compressor blows from using a thicker oil, it was going to blow anyway.

Sat Jun 08, 2024 5:21 pm

Thanks, Guys! One of the local shops thought that the oils won't mix at all, but that didn't make any sense to me as they're the same chemistry(pag). But there may have been something I didn't know. It's good to know that the different viscosities of pag oil should intermix. I've put 2 oz of 100 in the evaporator, and about an ounce and a half in the condenser. I will put a new receiver dryer in and put pag 46 in both the receiver dryer and in the compressor. Since it takes 5 oz in the compressor, and I'll have to look up how much in the receiver dryer, if i end up with pag64 or so, so be it.
What prompted the change of oil in a brand new compressor is that a friend of mine put a new chinese(aren't they all?) in his 88 westy and it prematurely failed. So I thought I would give mine a fighting chance with good oil. We shall see.
Once again, thanks guys!

Sun Jun 09, 2024 2:45 am

Read your product labels carefully. At least one company made a product PAG100, THAT WAS A PAG 46 OIL

:twisted:

There was a lot of lore that you can’t mix PAG OILS but there seem to be compatible ones now. I thought there were two classes of stuff thst did not mix, but viscosity mixing in class was ok.

Haven’t done any AC work since the LI move ….

Sun Jun 09, 2024 8:20 am

You can't mix PAG oils with PAO oils or mineral oil. That's true.

Sun Jun 09, 2024 11:54 am

khughes wrote: You can't mix PAG oils with PAO oils or mineral oil. That's true.

where pag and ester are mixable, usually used in a retrofit...which by now would be pretty rare to come across in the wild

Sun Jun 09, 2024 12:55 pm

skills@eurocarsplus wrote: khughes wrote: You can't mix PAG oils with PAO oils or mineral oil. That's true.

where pag and ester are mixable, usually used in a retrofit...which by now would be pretty rare to come across in the wild

You can mix them, but all the info I've seen is that just like PAG and PAO, the mixture separates out when the system isn't running. It can still get carried by the refrigerant, but whether that affects compressor lubrication or not is a question. Small amounts *I* don't feel can hurt anything since they don't chemically react.

No warranties expressed or implied :lol: