MW50 -Secondary effects were cooling of the engine .

[41Sqn_Banks]

Originally Posted by Mustang

But with the injection of wather methanol (MW50) , the overheat takes longer time, you can run saflely 10 minutes, in any condition, that's what says the Luftwaffe.

No way. Even if MW50 is authorized for a 10 minutes duration the maximum allowed oil and coolant temperatures still apply.

For example Merlin emergency power was authorized for 5 minutes, but the oil and coolant temperature must remain in the specified limits, see: http://www.spitfireperformance.com/dowding.pdf

The time limit means that the stress on the engine is that high that it will take considerable damage even without overheat after that time.