WAMASC Technical Information
The Use Of After Run Oil
I have been asked by a few modellers what I do to look after my collection of (mostly) four stroke engines between flights.
I can not stress enough how important it is to take care of these little marvels of engineering precision.
The use of a good after run oil (ARO) is the best and most cost effective way of ensuring a long and reliable service life from your engine.
A lot of Hobby Shops stock off the shelf ARO but I find these little bottles (generally about 200cc to 300cc) a bit of a rip off.
The cheapest ARO is automatic transmission fluid for cars. This stuff comes in 1 litre bottles and is way cheaper than the "genuine" modellers ARO. It is chock full of goodness in corrosion inhibitors and other goodies to look after our reciproctaing internals.
The by-products of combustion in our engines are very corrosive and it is important to get on top of them quickly after each days flying.
Step 1) After the last flight, run your engine dry of fuel or make sure you have defueled and dried the engine.
Step 2) When you get home, push a few cc's (you'll get to know how much with experience) into the engine crankcase breather with a syringe. Then spin it over with a starter motor to eveningly distribute it about the bearings, (4 strokes) camshaft and valve drive gear.
Avoid hydraulic locks as these can bend con rods and damage the motor. If you are concerned about hydraulicking your engine, remove the glow plug for this operation. Spin it over with your thumb over hte glow plug hole. It now acts as a sort of safety valve "blowing off" when the piston comes up on compression.
Store the motors with a cloth or some sort of absorbant material under it as some ARO will eventually find its way out due to gravity.
I tend to store my 4 strokes upside down and nose down to encourage the drainage toward the nose gear (cam gearing) and any excess down the push rod tubes.
Two strokes without crankcase breathing are an easier proposition - just a few cc's in through the carby to douse the bottom end. Spin over carefully avoiding hydraulic locks. Store.
Cameron Roberts
26 September 2006
