When i bought my C36, it had 63k on the clock. I did not know at the time, but it had a slight leak due to a worn headgasket seal.

I noticed it at 68K, as i finally saw some drops of oil on my garage floor. I guess it was bad enough to finally drip past the bottom engine cover.

I did get it replaced for $1300! Good thing to have an extended warranty.

Prior, I did not notice any abnormal engine temps.

Your call on what to replace, but obviously you should get it fixed asap. If money is tight, you might be able to get by a couple of paychecks until you can get it done...but try and do it sooner than latter as it's hard to say what kind of trouble can happen. Basically anything that can go wrong because of it won't be cheap!