Automotive Air Conditioning Information Forum

I have been pondering an oil question today.

Most will say use DEC Pag. Why? Because DEC Pag is capped at both ends in the structure of the oil. Claims and research show that it is less likely to attract moisture over SEC Pag.

What if DEC was a trademarked or unusable term? What if there are oils that are extremely good these days but can't use the term DEC?

I believe I've run into this very question. I'm not a legal expert or know all the fine details on specific brand marketing, and I'm not trying to create controversy.

So, for now, I'll use the term High-Performace oil.

Tim wrote: ↑Fri Sep 10, 2021 4:35 pm Because DEC Pag is capped at both ends in the structure of the oil. Claims and research show that it is less likely to attract moisture over SEC Pag.

I would tend to agree that in theory double end capped PAG should attract less moisture than a single end capped version, because single end capped would have a hydroxy (-OH) at the end.

However, in a sealed refrigeration system, not easy for moisture to get in, because such lack of seal would also let refrigerant out.

Cusser wrote: ↑Fri Sep 10, 2021 8:53 pm

Tim wrote: ↑Fri Sep 10, 2021 4:35 pm Because DEC Pag is capped at both ends in the structure of the oil. Claims and research show that it is less likely to attract moisture over SEC Pag.

I would tend to agree that in theory double end capped PAG should attract less moisture than a single end capped version, because single end capped would have a hydroxy (-OH) at the end.

However, in a sealed refrigeration system, not easy for moisture to get in, because such lack of seal would also let refrigerant out.

Agreed, moisture issues were always more related to proper service repair procedures. I know there are extremely good oil companies out there not using the phrase DEC. The biggest issue I see today is people leaving an open, then capped bottle on the shelf for 8 months. Expecting it to be a fresh bottle of oil because you tightened the cap. If this were the case, I'd not have tossed so many bottles of salad dressing in the trash.

Al9 wrote: ↑Sat Sep 11, 2021 7:17 am

Cusser wrote: ↑Fri Sep 10, 2021 8:53 pm However, in a sealed refrigeration system, not easy for moisture to get in, because such lack of seal would also let refrigerant out.

The thing is, double end capping seems to increase EP performance and even improve oil return. It's not all about the moisture.

There are oil enhancers and other additives that will do the same, yet not claim to be DEC. I keep thinking of BVA Oils in general. They have what I believe is some of the best oil-made. No claims, just a bottle of oil. Same with Lubrizol, which in my understanding makes the Add packs for more than one marketed oil around these days.