I have been letting my mechanic take care of regular maintenance on my 2009 CLK 350 up till now. But today I did the 80K mile service myself and also a tune-up with new air filers and spark plugs. I also wanted to take a look at the old spark plugs to judge the health of the engine.

First thing I noticed was that the airbox wasn't clipped properly on. The clip on the back of the engine wasn't on and neither was the front right clip. After getting the airbox off it was obvious why. Quite a few of the clips were badly bent and the front clip wasn't in its mounts on the engine.

I then checked the oil level and it was way high, all the way over the plastic gauge at the end of the dipstick.

Then I got under the car to remove the panels for access to the sump drain plug. 3 out of 8 panel screws were missing.

Torques on the various bolts were all over the place.

All it took to get the aitbox properly mounted was to straighten all of the clips on the box and the front engine cover plus insert the bottom of the front clip into the hole designed for it.

I took a run to the hardware store to get screws and washers so I could mount the underbody panels securely. I'll order the OEM ones and have a store of spares.

When filling the oil it showed half full after 7 liters had been added. Starting the engine to fill the oil filter and letting it sit for a while got it down under minimum and at the end I had put 7.5 liters in and up to half full. I'll check it again after the next run.

A pleasant surprise was that the knocking the first second or two after start was due to the overfill. Now it sounds the same all the time.

I didn't have energy to flush the brake fluid, but will do that another day.

Bottom line. I feel much more comfortable that the job is done right if I do it myself. Even good mechanics are in too much of a hurry to get to the next car in line.

I have been doing the routine maintenance for a pretty long time on the clk. If it doesn't involve "heavy lifting", high knowledge, special tools, or isn't an emergency due to a breakdown, I will generally try it myself. There is the satisfaction of doing it and I stay aware of most every nut, bolt, fastener, scratch, and nick on the car.

I completely agree that mechanics are in too much of a hurry to do a great job. My indy has an awesome reputation, but I've noticed a few things his shop has been careless about, including leaving a strut bolt cap (a little rubber cover) laying loose in the engine bay (I think he lost the other one so I had to buy a new one on ebay), and partially-tightened screws in the airbox (from when he checked the air filters).

I wish I had a huge garage with a lift so I could do everything myself safely. Unfortunately, I currently live in an apartment, so that's not an option. And my single-car garage is too small to work in.