I second this. I have used both, with positive results. I've been using this Chevron additive for probably 20 years. I can hear the difference at the exhaust pipe when I use the Chevron with Techron additive maybe every 10k miles or thereabouts. Chemtrol B-12 is another one that works, per this forum..I am a longtime user of the Lubegard 60902 ATF Protectant. Can't remember when it first crossed my own radar, but probably over ten years of positive results in our Odysseys. I only used it to fix problems, and it did.
My background is in chemistry, and I did a bit of research to find out "what" is in Lubegard products. The Lubegard people are actually open about this, and they use long chain wax esters, which essentially duplicate the physical and chemical properties of sperm whale oil. These compounds are excellent for heat exchange and assist ATF thermal stability (there are some interesting engineering papers on how hot ATF can briefly get at the interface between clutch frictions and steels in an automatic transmission during a gear change). Ergo, I now use it as a protective measure in all of our family vehicles.
Really, Lubegard products and Chevron Techron and ATP AT-205 are the only additives I use because of their track record.
I was able to find out the chemical makeup of the primary constituent compounds in Lubegard ATF protectant, and given I had problems with my Odysseys, and a positive experiene from Odyclubber Jerry O, that's why I tried it. It worked, as advertised.
Regarding Techron: the only word I've been able to find about this is that Techron is essentially very similar to the detergent compounds added to Chevron gasoline, but in its unadulterated form in a bottle for concentrated use. I'm comfortable enough with that, and its very positive reception over many automotive forums, to use it as a once-per-year application for fuel system maintenance. As well, it did work for me on my Honda CRX, to fix a tremendous problem.
If you are already using fuel stabilizer with good results for your small power equipment, I see no need to add anything else.
Regarding ATP AT-205, both of my Odysseys developed significant rear main seal leaks. ATP AT-205 has a dedicated following on various mechanics' forums, and was given a thumbs up by a few Odyclubbers, so I had nothing to lose (either ATP AT-205 was going to fix the leaks, or I was going to have to remove the transmission to replace the crankshaft rear main seals). ATP AT-205 fixed these problems. I continue to use it in our Odys as a maintenance item.
That is it. I use nothing else, as modern automotive fluids (ATF, coolant, oil) are almost always sufficient for normal operation of a vehicle that is not enduring any problems.
I know nothing about Marvel products, or their chemical makeup, so I don't use them. Same for Lucas products; I don't use them. Modern motor oils are a wonder of modern petroleum chemistry. If you have noisy lifters on startup, I'd switch to a high quality synthetic like Mobil 1. I use Mobil 1 EP.
In general, I am "anti additives" for normal operation of a vehicle. Lubegard and Techron are my personal exceptions ... I use them for normal operation. I used ATP AT-205 to fix some major problems (oil leaks).