Any horticultural oil will do, just read the label. Here is one:https://www.amazon.com/Southern-Ag-Parafine-Horticultural-16oz/dp/B004QIZUYI, info: https://www.unce.unr.edu/publications/files/ho/2013/fs1320.pdf. and more, with lists (there are more ways to go than just neem) http://www.clemson.edu/extension/hgic/pests/pesticide/hgic2770.html. Currently, I am using for the first time this oil: https://www.amazon.com/Conc-Org-Garden-Spray-Pack/dp/B001CJ6764?ie=UTF8&ref_=cm_cr_arp_d_product_top to see if works on spider mites on a certain rose bush I let get infested on purpose to experiment. I paid 14$ for a quart. You really need a good sprayer to apply an insecticide if your tree is large.