Thread: Gas differences

Hello all, I have enjoyed reading many great posts on this forum, and have a question for you.

I have a mig welder - occasional / hobby use - it is an older Uni-Mig 235 (max 250 amps).
Mild steel use (0.6 wire and 0.9 wire) and used Argoshield light in the past.
Welding the lighter stuff up to 6mm. Dip-Transfer

I am looking to hire a cylinder of shielding gas (E size) which - if I don't forget to turn off the tap - will last me a long time.

Comparing the different suppliers and mixes that might suit gives me several to choose from.
BOC have
Argoshield Light= 3% Oxygen, 5% CO2, 92% Argon
Argoshield 40= 5% Oxygen, 95% Argon

Supagas has
Supa Argon 52= 2% Oxygen, 5% CO2, 93% Argon
Supa Argon 07= 7% Oxygen, 93% Argon

If I remember rightly, CO2 gives a bit more "bite" so better penetration.
What differences would I expect to see between Argoshield 40 and SupaArgon 07?
Is this a case of suppliers being different in their mixes just for the sake of it?

Are the Tri-mixes generally more expensive?
I have not price-shopped as yet.