Looking at changing the coolant, & wondering what to use. I was after Castrol Radicool SF-O recommended on their website, but it is not easily obtainable in retail (<10L) quantities in my area.

The main ones easily available are Nulon or Penrite & I want a concentrate rather than premixed.

Can anybody suggest a preference between Penrite Blue 7 year & Nulon Red 8 year. These are both OAT coolants, & would require a full flush of the system, which I will be doing.

Any information would be greatly appreciated.

Cheers,

Lionel