Lawrence,
Thanks for your help. the main reason for this question is because one of our vendors uses this gas mix and I need to know if there are any strength problems as we use 96AR/14O2. All of our welding is on 11ga. 1/4 to 3/8 mild.
While it is true that you can take care of all of your welding needs on carbon steel with basically one gas, there are some advantages to adding a bit of oxygen to the mix. With the lower transition current required for ionization, the puddle forms at a lower arc voltage. I found though, that if you are welding a filet, the puddle will actually climb the vertical web a bit, which will not only help in better wetting, but can also reduce undercut. There is a lot of controversy over whether the gas companies are "gouging" their customers with these "ultra" mixes and many describe it as "smoke and mirrors", but in the real world, there are advantages to these products. If it wasn't worth the effort, the gas companies would not be spending the money to test and market these products.
As stated above, more information is required before an educated answer can be given.
regards
Sparx