anti-freeze

[norseman]

Sorry if this query has been raised before (never have much success with a search facility) but can OAT (red) antifreeze be safely mixed with the existing BLUE A/F already in our cars? One has an all-alloy engine, the other an iron block & alloy head.
Thanks for any replies.

 

[Mottie]

No. Drain it out, give it a few flushes and fill with fresh.

 

[Burnerman]

Personally Id change the antifreeze for the red stuff.....its not supposed to mix and the corrosion inhibitors are compromised. It also lasts much longer. Do the same to both vehicles if you can, and then you just need one top up solution.
John

 

[norseman]

Sod it, bought the stuff for topping up & didn't think of checking the label. I'll take it back & exchange for the blue which will suffice until the cars need a coolant change.
Thanks for the replies folks.

 

[Avocet]

As has been said, no, they don't mix. Also, the colour isn't an infallible guide as some manufacturers have their own colour (green in sme Nissans, for example). The basic antifreeze is the same ethylene glycol, but the additive packages vary (including the dyes that they use). Mixing the two used to form a dreadful sludge, hence the requirements to flush several times, but I think in recent years, that's not so much of an issue. Protection will be compromised, however. If your cooling system has any "yellow metals" in it (most likely copper or brass), you shouldn't use the newer "OAT" stuff.

 

[norseman]

Thank you Avocet.