You don't need to do anything as long as everything is running fine. When your engines start to act sluggish or stall or need more power, it is time to reoil, pick lint, wipe grim off the wheels of the engines and rolling stock. Clean the track every time you run. Dirty track is the cause of many problems. We use isopropyl alcohol [denatured painter's alcohol]- we buy it in a quart can from Home Depot or you can get it at a hardware store. The kind you get at the grocery is rubbing alcohol and it just doesn't clean nearly as well.
We use LaBelle #108 oil which is what we have found works absolutely the best. It is compatible with plastic and Marklin Z. All of Marklin's gears are metal but there are plastic frames - around the motor and trucks to mention a few. We use a fine hypodermic needle, such as diabetics use, filled with the oil. There are oiling instructions in the box underneath the engines. Just a fine drop where you see a metal gear, that goes for the axles too. I oil the axles on the cars too, it is our personal preference. The 'spoke' end of each wheel needs a fine touch of oil and also where the rod rides on the car's truck.
A fun chore - and it is really - is to take the wheel sets out and wipe them of accumulated grime and lint occasionally. They will thank you and roll to prove it. When Marklin doesn't roll smoothly, there is something that needs something. Look for lint and grim in trucks where the wheel sets were or a speck of plastic flashing.
Many, many miles down the track the engine's motor will get dirty just like a car. It is a 3-pole motor and when the `poles' get filled with carbon the engine needs a complete cleaning. We take the diesels and most of the electric engines totally apart for cleaning. The steams don't need to be taken completely apart and requartering them when it isn't necessary is a bear.
We wipe our track with chamois [less lint] instead of Q-tips or cloth. We buy what ever size chamois available, 18" sq. or 1-1/2 ft, 2 ft. Follow the instructions, wash in very mild soap, rinse, don't squeeze or hang out in the sun to dry. Handle to soften. Glenn cuts them in inch to 1-1/2 " size. What every fits you finger. I fold it a couple of times so it becomes about the size of the track and works like a pad. We found some extra virgin alcohol at an electronics' shop and its 99% purity we found out makes a difference. The brand available to us is made by TECH SPRAY Isopropyl Alcohol - Cleaner/Degreaser #1610-P for $7 /16 oz. or $15 a gallon. I use the same to clean wheels much better than the painters or rubbing type of alcohol.
We use meters on all our main lines, 3 volts is about average for running. We find that any time we need over 4-1/2 volts, it is time to look for an underlying reason. Like oil or a dirty armature.
Finally, ALCOHOL CAN BE TROUBLE too. DO NOT use it where there is paint. It will take off paint, red, black, silver, etc. - it doesn't have a preference.
With best regards to all,
Glenn and Sandy Stiska
Largo, Fl 33771
U.S.A.
stiska at idnsi.net