Stihl weed eaters are simple, well-built machines that require minimal lubrication procedures. Their simple design includes only one area that requires regular lubrication, and that is the gear box found at the end of the drive shaft that connects directly to the cutting head of the weed eater. No other parts require grease for lubrication.
Lubricating the Gear Box
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The gear box encloses a series of gears that transfer engine torque from the drive shaft to the weed eater cutting head. Many different cutting heads may be present, from a brush cutting attachment to a bump-feed trimmer line attachment. This area will absorb a large amount of energy from the power of the engine. It will also have to deal with large amounts of resistance placed on it from the weeds, brush and other materials placed in front of it.
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Stihl had developed a specific lubricant for this gear box. It is available in small tubes that connect directly into the gear box for quick and easy dispensing. The user simply removes the filler plug from the gear box housing, threads the tube of gear box lubricant into the hole and squeezes about 1/5 ounce of grease into the gear box. The gear box housing does not have to be completely full of grease. This would interfere with the correct workings of the trimmer head. Only a small amount is required to keep the gear box in working order. When grease has been added to the gear box, remove the tube of grease and reinstall the filler plug, tightening it so it will not vibrate loose and allow the gear box to become contaminated with organic waste materials.
The gear box does require regular maintenance. Because such a small amount of grease is required at a time, the gear box must be opened and visually checked on a regular basis. If the Weedeater is used every day, the gear box must be visually checked weekly. If it is used less often than daily, it should be checked monthly. Grease should be added to the gear box whenever it is required to keep the gear box in good working condition.
Engine Lubrication
Stihl brushcutters utilize 2-cycle engines that do not require grease for lubrication. They require special 2-cycle engine oil that must be mixed into gasoline at the correct ratio for lubrication. The correct fuel/oil mix ratio for Stihl 2-cycle engines is 50:1. This ratio is easily met when adhering to the following mixing quantities: 1 US Gallon = 2.6 fluid ounces 2-cycle oil; 2-1/2 US Gallons = 6.4 fluid ounces 2-cycle oil; and 5 US Gallons = 12.8 fluid ounces 2-cycle oil.
Oil for 2-cycle engines is available in petroleum-based, synthetic, and environmentally-friendly, biodegradable formulations.