Matlab Grid lines with different color on one axis
plot(x,y,'--g')
set(gca,'Xcolor',[0 0 0],'Xtick',[12e3,14e3,18e3,23e3,30e3,37e3,57e3],
set(gca,'Xcolor',[0.5 0.9 0.5],'Xtick',[10e3 16 28e3]);

x=-3.14:.1:3.14;
y=sin(x);

h=plot(x,y);
ax1=findobj(gcf,'Type','axes'); %save first axis handle

%set first stype
set(gca,'Xcolor',[0 0 0],'Xtick',[-3,-2,-1,1,2,3],'gridlinestyle','-','xgrid','on')

%create new axis
ax2=axes('position',get(gca,'position'),'Visible', 'on');
set(ax2,'YTick',[],'Xcolor','blue','Xtick',[-2.5 0 2.5],'xgrid','on','color','none'); %color none to make the axis transparent
set(ax2,'xlim',get(ax1,'xlim')) %resize 2nd axis to match 1st