Keep your nitro running consistently

Your nitro engine can last many gallons if properly cared for. Here's a few things you should do after every run, and some others you should check at regular intervals.

At the End of a Day
At the end of a day, there are several steps you should take to insure the longevity of your nitro vehicle and engine:

• Run the tank dry, or drain it, and start up the engine with the glow start attached to burn excess fuel out of the engine and fuel line.
• Clean up the model overall with cleaners or compressed air; be sure not to wet any electronics, and do not remove the air filter during this cleaning. The air filter itself can be removed and cleaned afterward, or the element replaced when it gets soiled.
• Inspect all parts of the vehicle for damage or loosening fasteners.
• Remove the air filter, open the carburetor opening either by hand or with the transmitter, and put a minimum half teaspoon of after run oil into the carburetor. Crank the engine over to move the ARO around inside the engine to coat all internals.
• Rotate the engine by the flywheel, by hand, until you feel the compression that tells you the piston is reaching top dead center. Now rotate the engine back 180°, allowing the piston to come to rest at bottom dead center. When the engine cools, the piston sleeve will contract, and if the piston is at top dead center it will trap the piston in this position making it hard or impossible to start next time. This is particularly important with new engines, due to the newness of the sleeve taper at the top of the sleeve.
• Inspect the pit or setup area for dropped tools or parts and give RC'ers a good name - clean up after yourself, picking up any discarded packaging, glow plugs, and clean up any spilled fluids.

A Word About After Run Oil
Also a highly debated topic, the use of After Run Oil is generally a long-term-storage consideration. If you run every day, you really don't need it. The problem is, most of us don't know how long it's going to be until we come out again, so ARO treatments after every run are a very good idea.

Watch this site for an extended article on After Run Oil: what it's made of, why you need to use it, and how much. Briefly, alcohol-based fuel is hygroscopic. This means it condenses water out of the air and quickly and forms water droplets on any surface. Inside your engine, this can lead to rust on the internals after a very short time.

After Run Oil is used to drive out any excess fuel and replace it with a water-displacing oil. A few drops won't do and is a waste. You need to use enough ARO to completely flush and coat the engine, often enough to make it hard to start the next time you run. A half teaspoon is a decent dose to achieve this coverage.

As previously described, apply through the air inlet and turn the engine over, allowing the ARO to find the same path through your engine that the fuel does, and sufficient lubrication will reach the combustion chamber. While many nitro owners additionally remove the glow plug and put some in the glow plug hole, it is this author's opinion this is not required and can be detrimetal for four reasons:

• The ARO finds it's way to the combustion chamber via the method described, through the air inlet and by turning the engine over, so ARO in the glow plug hole is just not necessary.
• Any oil you drop down the glowplug hole is immediately blown out when the engine is turned over.
• Frequent removal of the glow plug scratches and distorts the copper glow plug gasket, leading to compression loss. This is one less time you will need to remove the plug.
• This method can allow dirt and dust to enter the engine via the glow plug hole, even with rigorous cleaning before removing the plug.

What to use? The formulas of hobby-grade after run oils are a well-kept secret, but simple comparison shows most of them contain, at least in part, Marvel Mystery Oil. MMO, or a 50/50 mix of MMO and another good water displacement oil, automatic transmission fluid, is an inexpensive and acceptable substitute for expensive ARO's. WD-40, although used by many racers, will work but contains solvents and low level acids and is not the best long-term ARO solution.