Here are the brands I recommend for your oil,
1. Mobil 1 Synthetic
2. Mobil 1 Synthetic
3. Mobil 1 Synthetic
And the weight, 15w-50
Especially for that Lotus S4 you have!
For any high revving engine that deals with a lot of heat it's the only brand I'd use. Reduces friction and wear to incredible amounts. My car has only had Mobil 1 in it and when I did my valve adjustment at 120,000 miles only one valve needed to be adjusted (out of 16). That's pretty amazing if you ask me. No scorching or discoloration (browning) of the oil on the head either. I as well as the previous owner change(d) it every 3,000 miles. When I used to turn wrenches all our engine builders told us to use Mobil 1 exclusively. As for the seals and such, I've never had any problems period. My Turbo seals are still good and although I haven't pulled the head, I'm not burning oil so I'd assume my valve guides and piston rings are in good shape. By the way, every Porsche that rolls off the assembly line has Mobil 1 in it. If it posed any problems to seals and such do you think they'd expose themselves to the liability if it were to cause expensive problems that could result in them having to rebuild thousands of engines due to seals going bad.
Now for the Gear box, use GM Synchromesh. I'm not kidding on this one. Much better than Redline or Mobil 1. Improves shifts like you wouldn't believe. Try it and you might actually be able to get that QV into second before the gearbox warms up