It's not that the 4 seasons chart is flat out wrong everywhere. Most of the time they're pointing you to the underhood labels anyway. Problem is, they do have some incorrect info in some places, making you verify the chart as you use it.
On a few occasions the factory literature gets behind in any changes or even flat out typos and wrong info, but that's rare. The underhood labels won't change but don't always tell the entire story. And that's why I wonder that if you put just 6 ounces in the system, 3 in the compressor and 1 in the evap, 1 in the accumulator, and one in the condenser, for example, the CSM still wants you to put 2 more ounces into the accumlator to make up for the oil sucked into the desiccant that ain't coming out. So 8 ounces isn't really off that mark- problem is for me it doesn't tell you why they state 8 ounces on the 4 seasons chart. GM manuals sorta get around to mentioning that. There isn't a "here's what you do step by step" laid out in a GM manual. You have to read between the lines.
Additionally, the 1978 CSM discusses how new GM units come with 5.5-6.5 ounces of oil in the compressors and to drain it out before installation and then refill with 3 ounces of oil. Well, later GM compressors came without oil. Even has a tag on it that says basically it's shipped without oil and you need to add oil to it. They put just enough oil in it during assembly to keep the bearings lubed and that's it.
And that's probably the best way to do it. Not going to argue with professional experience.
Thinking more about it, approx. 8 ounces of oil into a totally new system with a new accumulator is probably best to allow for the desiccant sock to absorb a couple ounces of the oil, allowing for 6 "free" oil to roam the system and keep the compressor constantly lubed, which is the main point anyway. And anytime you open the sysytem it's probably a good idea to get a new accumulator anyway because letting the desiccant absorb moisture from the air just sitting around open will saturate it. Keep in mind, check to see if it's compatible desiccant for the type of refrigerant you're using. The newer stuff claims to work with both 134 and 12 (XH7 and XH9), but the original old school GM accumulators are just for 12 (HX5). Of course, if you don't replace the accumulator, you can skip the extra 2 ounces of oil.
My thoughts are make sure there's at least 6 "free" ounces minimum with an R-4 system, but a couple ounces more ain't going to hurt it when you replace junk in the system. GM tends to imply you should anyway with new accumulators. My concern is that R-4's have no oil reservior so all the lubricant has to come from the refrigerant/oil mix as it passes through the compressor so 6 would be the absolute minimum.
