Keep in mind, I'm a newbie.

Alright, so I finally got a Supra. Its a 1988 Mk3 Turbo Targa 5sp w/ 107,000+ miles completely stock. However, its leaking oil. The previous owner said he stopped driving it over the summer so maybe the cam seals or front main seals swelled up or something. He gave me the valve cover and oil pan gaskets when I bought it. So being that it leaks, I've been topping it off with high mileage synthetic 10W-30 oil as I drive to and from school.

Someone recommended lucas oil treatment as a temporary fix. Should I try that for now till I can find where its leaking from? Also, its really cold where I'm at (upstate NY) and I've been reading about how 10W-30 oil is too thick on start ups; any recommendations on oils for 0 to 30 deg F weather?