Vintage Cars: 85 mercedes 380sl, gas tank, timing chain

Question
I'll be picking up a 1985 380SL I purchased in about 1 week. What type of oil would you suggest I run in it? It seems that a lot of the reports I've seen say these cars tend to be under powered. Are they really that bad? Also,what should I should I put in the gas tank to help run older fuel through and help clean out the system ( cars been sitting for awhile ).

Answer
you need to run 10 -40 . I actually run 15 -40 in mine (450) Sl , depends on climate, but 10 -40 is safe / You can try any fuel system cleaner , I like lucas , but if it is really old fuel , you need to dump it if you can .
Yes 380's are a bit of a  slug,  The 380 SL was the least powerful of the US imported R107 roadsters about 155 HP as compared to 185-190 in the 450

Good thing about the 85 380, double row timing chain and better ACC.
Good luck!