Had a chance to buy some Lucas 15-40 for 12$ a gallon . I'm sure thats a good price but my problem is availability if I need a quart here or there after I use the gallons. I had a thread in the shop section on Rotella prices. I really can't see any superior reason to use the Lucas. I do know they make some good products. One product they offer is an engine oil leak sealer. I have 3 engines leaking out the rear main, not pouring or nothing. I'd roll the dice on this. Does anybody use this?