Brian, indeed, there is absolutely no info on the forum on the Lucas oil, and to be honest, no info on the Lucas 10W-60 anywhere on the net, but all the other oils you mentioned have been discussed.
Trusting a seller to recommend the best product is not very wise, they usually recomment the products they sell, hence the utility of searching the forums. I personally have been using stuff like Castrol 10W-60, Selenia 10W-60, Valvoline 10W-60, Valvoline 5W-50, Penrite SIN5(5W-60) and Royal Purple 20W-50. My old JTS used to burn a little oil, but only Selenia, when I used Castrol the oil consumption was far less. On Valvoline the oil consumption stopped all together. But I never drive above 3500RPM unless the oil is at the right temp(no oil temp gauge on the JTS though, but in 15-20 minutes of driving it should have reached the right temp).
In the GTA, again, Selenia(used by the folks I bought the car from) was the poorest oil, the car burned a bit of oil after 4000kms. With Castrol(the only oil available when I did the first oil change) it stopped using oil, and with Penrite and Royal Purple there was a subtle change in engine noise.
PS. 1l every 1000kms or 1l every 1000miles is still a lot of oil used. This way, asuming you change the oil every 6000miles, you will top up 6l between oil changes.