PeterB Hi Greg
On reflection I don't think the Prenrite blue OAT coolant is equivalent. I've just order the original (most likely HOAT type) coolant, only $9- more.
P.
https://www.nulon.com.au/amp/products/cooling-systems/green-premium-long-life-coolant-100-percent-concentrate
I've got a fleet of p1 cars using that and zilch issues including my s40 race car
Just mix it 50/50 and run it after flushing out all the old coolant