New ZR1 Owner

[jrtoffroad]

Hey guys, just wanted to introduce myself. I purchased DMark's 91 ZR1 last week and absolutely love the car.

Ran to the track (Alabama International Raceway) Friday night and very happy with the car's performance...just not so much the driver's. Really struggled to get a good launch. Best time was a 12.6 @ 113mph, which actually was my first run of the night before any prep. After letting the engine cool a little my MPH jumped to ~116, but times suffered (~12.85) due to excess wheel spin. Oh well, just need more practice.

Couple maintenance questions:
-Noticed a small oil leak on the front of the engine, any suggestions on where to start tracking it down?
-It seems after driving the car hard it likes to idle a little higher (950 vs. 650) any one familiar with this? I was getting a little surge at idle, and found a bad vac line to the MAP sensor which seems to have cured that problem
-What's the consensus on the best plugs & gap for this engine (mildly modified)?
-And finally I see most people seem to really like the 10w-60 castrol oil for the trans...but since the stock oil was a 5w-30 weight, would it be a bad choice to run a more readily available engine oil closer to the stock weight? Guess I'd at least like to know what makes the Castrol so popular for this trans.

THANKS!
Jordan