I don't need a standard/simple answer, I need someone that has really looked into cleaning down. 30 years ago while working at a backpacking store in the Midwest I sent a warm Snow Lion down sleeping bag and a very warm down jacket (North Face I think) to a speciality shop in California that cleaned down things. When they came back they both were very much less warm and less loft.
I bought a Gortex covered Marmot Gopher 5 degree bag that I have needed for warmth and used for over 30 years backpacking about 2 weeks a year. I've never trusted washing it because of that previous experience. I've washed off the surface area where my face is, but always have used with clothes and have been very care careful with it and have noticed no warmth difference in the 30 years.
Am I better off just leaving it alone or would it actually help to clean it now?
Maybe an REI person knows the answer.
From your description of the treatment it has received, I would not think there is any need to clean it. Does it still retain its original loft? Still warm? Leave it be....
I have had a couple of down bags washed, including washing a North Face bag purchased in 1977 twice. That bag is in regular use with a homeless person now.
Since you are mentioning a 30 year old bag, I believe I can speak to that experience. I think new bags are treating their down with chemicals that perhaps give them different properties. Maybe even properties that allow them to be washed with less degradation, but I doubt it. My experience is the first time you wash the down bag it loses at least 10% of its warmth. It seemed the second time I washed the North Face bag it didn't get much worse.
I also have worked in management in an outdoor company at Lake Tahoe. We sent our bags to Sierra designs to have them washed. I recall discussing it with the folks at Sierra designs and they mentioned you would lose loft and some performance after you wash the bag the first time. However for some bags they were so dirty and full of salt that the difference was negligible.
I guess the final answer is, how dirty do you think your bag is? Is it compromising the performance right now? Why do you want to wash the bag? Do you have a use for it if its performance characteristics are somewhat diminished? Do you have a personal connection to the bag or is it time for a new piece of equipment?
I can understand wanting a piece of equipment to last a lifetime. It is rare though with heavy use. Sometimes you just have to break down and support consumer society. Buy well.
A couple years ago I washed a 40 year old bag using Nikwax Down Wash Direct (https://www.rei.com/product/890310/nikwax-down-wash-direct). I filled the bathtub up with warm water and added the Down Wash Direct. Then I added the bag and mushed it around (how is that for a technical term?) trying not to lift it out of the water so as not to rip any baffles. The water turned gray from dirt and grime. I then pulled the plug and softly and carefully pressed down on the bag to remove as much of the water as I could. Then I filled up the tub again to above the bag and repeated the mushing to rinse. The water was still a little gray so I repeated. After the second time the water was pretty clear. After getting as much water out of the bag as I could, I then put it in the dryer with a couple tennis balls on low heat until it was dry. After everything, the bag looked and felt new. I think the loft, depressed from years of use, nearly doubled.
I am not backpacking any more so I don't need it to be better but it is hard to believe it is dirty. I've been very careful with it. I guess I was thinking about does salt from occasional sweating seep into the bag when I always wear clothes in it. If I ever give it away I will probably want to clean it (I've heard of the tub method) but for now it would not offend anyone if they saw it. Thank you all for your opinions. And I am sentimental about all my gear :-).
I understand that "sentimental" thing, I often find it hard to part with old gear that I no longer use but is still useful. Some of that gear have a lot of memories associated with it.
Years and years ago I tossed an old down bag into a regular washer with regular detergent. It ended up with the down in clumps. A friend said toss it into a dryer with 5-6 tennis balls and it fluffed up and spread the down back out. Proper detergent might have been far better but I didn't know about it then but the tennis balls worked very well. Good luck!
The Tennis Ball trick def works really well. I keep three in my laundry room for this exact reason. I bet the washtub, and then tennis ball dry (On no heat), works the best. Good luck and let us know the results!
I have hand washed a couple of 30-35 year old down bags using a teaspoon of Dawn Dish soap with cold water in a full bath tub then let them air dry outside. The bags didn't lose their warmth in my opinion and maybe this was not something I should do according to down cleaning experts, but these bags do not have the same sentimental value as it sounds like yours do.