have you simply got an air lock in the system that needs bleeding out ..... bleeding air lock
AND as for that snowmode stuff and wheels and tyres, well, my 56 plate Honda Legend 3.5 ltr is an automatic with simply
ALL WHEEL DRIVE and is purported to be brill in the snow whenever we might get some, or indeed any more that I won't be staying indoors to try to simply AVOID
I don't need an SUV but do acknowledge that my beloved Ls400 is simply pathetic and all over the place in ice and snow
Malc