Did an oil change this weekend and since I hadn't cleaned the oil tank yet, I did that.  I've decided to do my oil changes at 30-hour intervals.  My detailed checklist for oil changes is at the bottom of this post.

Oil drained....

New filter on

The magnetic plug was checked (all good!) and safety wired back in place.

I loosened the ring clamp holding the cover on, the two worm-drive clamps, and was able to slip the tank out the bottom.  I noticed that when I did this a good amount of oil drained out, so just pulling the plug doesn't really get it all out.

Considering I hadn't cleaned the tank, it didn't have much lead sludge.  Of course, I've been using Decalin for a while, which certainly helped.

Clean as a whistle!

Latch safety wired back in place.

Drain plug back with a new crush washer.

Safety wired...

Since things need to be done in a specific order I created a detailed checklist for an oil change:

• If replacing spark plugs (every other oil change), gap 8 of them to 0.6mm (0.023") to 0.7mm (0.027")
• Warm-up engine to operating temperature
• Remove upper cowl
• Remove keys!
• Detach air intake from the NACA duct
• Remove lower cowl
• Burp engine
• Get sample container
• Put on gloves (there's lead in that oil!)
• Remove drain plug  bolt (using 17mm and 19mm wrenches (the 19 is used to hold the tank nut so you're not twisting the tank))
• Drain oil - Take a sample from mid-stream of oil draining for oil analysis (I use Blackstone Labs)
• If cleaning the tank (every third oil change) ( Video Part 2 below for how to clean the tank of lead sludge):
• Loosen top cover and two worm clamps
• Remove tank and clean
• Reinstall tank and cover
• Safety wire cover latch
• Reinstall drain valve with new crush washer to 25Nm (18.5 ft-lb) (Groove facing down)
• Safety wire drain plug bolt
• Prepare a new filter with an oiled gasket surface
• Remove oil filter, protecting components underneath with paper towels/towel since oil will leak
• Put on new filter until fully touching
• 3/4 more turn
• Magnetic plug:
• Remove safety wire
• Use paper towels to protect parts from dripping oil
• Use 16 mm socket to loosen (may need a long-armed wrench)
• No whiskers longer than 3mm in length
• It should feel like a fine metallic paste
• Clean plug and re-install to 25 Nm (18.5 ft-lb) (Really should be 100 in-lb (8.33 Ft-lb) because threads are oiled)
• Safety wire
• Remove dipstick (so you’re not covering it in oil)
• Add 2.5 L
• Turn prop 20+ times
• If replacing spark plugs (every other oil change)
• Remove spark plugs and inspect (see below)
• Inspect cylinders & valves with a boroscope
• Put thermal paste sparingly on spark plugs threads (3 threads closest to electrodes should be clean) and install to 20 Nm (177 in-lb)
• Put lower cowl on
• Reattach air intake to the NACA duct
• Run engine to operating temp and make sure oil pressure rises within 30 seconds
• Remove keys
• Check for leaks
• Burp engine
• Check level before adding the final .5 L (Should be in the upper half of the min/max range (max if you're going on a long flight))
• Put upper cowl on
• Note Engine Time & Total Time in Engine Logbook
• Cut open the oil filter to inspect.