I tried with a few different types of fat, and found butter to be the best. (i was attempting a vegan flapjack)
I also found it was good to smooth down the mixture with the back of a spoon before baking.
I'm using 250g butter, 165 suger, 80 treacle. 330 oats, and about 25 minutes at around 180 degrees, but my oven regularly seems to work 20 degrees c below most recipes.
Plus other bits, liek fruits and nuts. It seems to stay together - I leave in in the (buttered) tray for for 10 minutes or so before trurning out and then cut with a good bread knife when cool.
Hope this helps, and I'm very keen to hear other recipes, specifically for vegan flapjacks. (i get that way occasionally).