A long as you're not burning oil, leaking it in significant quanitities, or have a motor on it's way out (knocking/excessive valve tap,etc..) it would be best to stick with 5w20, or 5w30. A 5w30 will flow the same as 10w30, once it's hot. The 10w30, however, will not flow as well when "cold", and will take a bit longer to lubricate your engine at startup.
Again, unless your motor is already showing signs of significant internal wear (burning oil, knocking,etc...), I would not recommend the Lucas. Again, it tends to "thicken" the oil. Unless your motor is already worn, or is used under sever load conditions (heavy towing and/or a heavy duty vehicle, racing,etc...), thn there is usually no need for what the Lucas does. In fact, it can be detrimental. Modern engines are built with much tighter clearances than in the past. These tight clearances require "thinner", or more "flowable" oils to be able to easily flwo through/around them. The Lucas will, much like the 10w30, not flow as well when the engine is cold. This, again, increases the amount of time it takes before the entire engine gets proper lubrication at startup.
As for the "High-Mileage" stuff, don't use it. It has chemicals to help "swell" hardened/shrunken seals. This can work for a short time, to stop or reduce an existing leak. However, once you stop using the product, or the seals just "shrink" again, it will leak alot worse then before.
I would suggest Mobil 1 Synthetic 5w30 Truck&SUV formula. Walmart has it in 5 quart jugs for approx. $25. With this, you can safely extend your oil change interval to 5,000-7,500 miles. This helps to offset the increased cost, over conventional. Also, I prefer the Fram ToughGuard filters (the silver ones, with the black "grippy" stuff on the bottom). They have better filtration then the orange ones, and they all have an anti-drainback valve.
