NEEM OIL

  Has any member use neem oil, ?

what do you want to use is for?

  Pest control for my brassicas,,,

 It is traditionally used in India (and other countries too I expect) and needs to be mixed carefully to ensure it acts as a repellent rather than killing bees, ladybirds etc. The use of it as an insecticide is not licensed here of course and so would not be officially recommended. It can be very poisonous so go easy... and it needs to be mixed with a soapy solution before using it to make sure it disperses through the mixture

The active ingredient of Neem oil is azadirachtin - it has insect growth regulator and anti-feedant properties and relies on direct contact with the pest for it to have an effect. In my experience it's often used in ornamental crops (pot plants, roses etc.) and organic growing systems in other countries against thrips.

For pest control on brassicas I assume you will have whitefly and aphids. I'd recommend either a detergent solution (from the garden centre also pest control products labelled as containing fatty acids are also basically soap) or for something stronger, an off-the shelf amateur product containing natural pyrethrins. Again these rely on contact action only so take your time to spray every one of them. For whitefly, spray just as the sun is going down as they will not tend to fly away as quickly as you attempt to spray them