So checked out my new to me C43, today for oil leaks, as I expected it's seems to be the oil cooler and valve covers! Any one have any tips on tackling the jobs, anything else I should do while I'm in there? Also what parts I will need to replace at the oil cooler?

Question #1) Are you sure it's the gasket, but not those valve cover baffles where the upper breather hoses connect to? You can reseal those with the black silicone they were originally sealed with. Also, if you do remove the valve cover you really should order the breather hoses. They are most likely going to be very brittle and break upon removal. It's easier to do this than wait for parts. Be careful putting the bolts back on too it's real easy to strip them. So just start them by hand.

Question #2) Take the oil cooler apart and replace the oval and round o-rings. This is likely the issue, it was common on the C36 and C43. It will be about $28.00 or so a gasket without my discount, but the price to pay to have a nice looking car with character.

Oh.. By the way, when you do your oil cooler gasket tighten those bolts real tight (not enough you won't get it off again, but you get the point). Not with a real big wrench, but a 1/4 does it well.

Thanks for the tips, maybe I'll hold off on the valve cover gaskets until I get the breather hoses!!!

Got the hoses but it's 20 degrees out!!!!

There is also a pressure test port on the timing case, you can see it by looking a bit above and behind the tensioner. It's sort of diamond-shaped and particularly on the earlier years of the M112-113 engines has a propensity to leak oil. Laterally it's close to the cooler, so leaks from it can be thought to be the cooler or filter housing unless closely investigated.

Thus, I would take a good hard look at that before proceeding. There is a redesigned part and gasket, it's like ten bucks and fairly easy to change except for the fan's intrusion to your work path.

Good luck.

Thanks