Seasoned A/C technician claims extra PAG oil is the way to go on automotive AC

[GON]

Working to learn servicing AC systems in vehicles.

Until I saw this video, all have stated how critical the exact amount of PAG oil is to maintain proper operation of an automotive AC system.

This technician, starting at 10 minutes in the video, claims auto manufactures use less PAG oil to reduce costs. He states more PAG oil is a good thing to do. He is the only technician I have heard state this. Of note, this technician appears older, and seems more familiar with older vehciles than the latest generation vehicles.

One thing I picked up on from his video, is that PAG oil absorbs moisture, and states moisture is the enemy of AC systems. This was meaningful as when I rebuild vehicles in front end collision, the condenser is exposed to outside air, and maybe for many months,

 

[AZjeff]

Calling @Chris142 for an opinion.

 

[clinebarger]

Didn't watch....1 or 2 ounces over likely won't cause issues depending on the size of the system....More than that will cause performance issues.

 

[Timmastertech]

There is exactly 1 place in the a/c system that oil needs to be and that is in the compressor. Over the last 10-15 years the OEMs have been designing compressors with oil separators in them to keep the majority of the oil in the compressor. The reason for this is that as oil circulates through the system it can coat the insides of the heat exchangers and affect heat transfer and performance. Too little oil is worse than too much oil but neither is desirable.

As far as moisture absorption, modern double end capped pag oils are no where near as hydroscopic as older generation oils. Best practice is if the system is exposed to air for a significant period of time that the desiccant be replaced.

 

[Chris142]

Calling @Chris142 for an opinion.

In AC class they said a system requires 3.5oz of oil per pound of refrigerant. Many systems do not have that much oil in them. If the amount of oil is marginal compressor life suffers and if there is any kind of leak without oil being added the compressor will fail quickly with catastrophic results.

I always go by the 3.5 Oz thing . Often add an extra ounce or 2. That miniscule amount extra won't effect cooling but will extend compressor life.

I have seen systems with double the recommended amount of oil working just fine. I think the extra oil thing is way over blown and over thought.

In class they also told us to add a couple ounces of ester oil to the mix .
Said it's a better lubricant than pag oils at higher pressures.
The truck I just did last week specs 9oz of pag 46.

It got 7oz of pag 46 and 2.5 oz of ester100