Eaton Fuller Transmissions are designed so that the internal parts operate in an oil circulating bath by the motion of the gears and shafts.
Thus, all parts are amply lubricated if these procedures are closely followed:
- Maintain oil level. Inspect regularly.
- Change oil regularly.
- Use the correct grade and type of oil.
- Buy from a reputable dealer.
Eaton 6609 Service Manual
The use of mild EP gear oil or multi-purpose gear oil is not recommended, but if these gear oils are used, be sure to adhere to the following limitations. Do not use mild EP gear oil or multi-purpose gear when operating temperatures are above 230°F (110°C). Many of these gear oils, particularly 85W140, break down above 230°F and coat seals, bearings, and gears with deposits that can cause premature failures.
If these deposits are observed (especially a coating on seal areas causing oil leakage), change to Eaton Roadranger CD50 transmission fluid, heavy duty engine oil, or mineral gear oil to assure maximum component life and to maintain your warranty with Eaton. (Also see "Operating Temperatures".)
Additives and friction modifiers are not recommended for use in Eaton Fuller Transmissions Proper Oil Level:
Make sure oil is level with the filler opening. Because you can reach oil with your finger does not mean oil is at proper level. (One Inch of oil level is about one gallon of oil.)
Draining Oil
Drain transmission while oil is warm. To drain oil remove the drain plug at case bottom. Clean the drain plug before re-installing.
Eaton 6609 Transmission Service Manual
Clean case around filler plug and remove plug from case side. Fill the transmission to the level of the filler opening. If the transmission has two filler openings, fill to the level of both openings. The exact amount of oil depends on the transmission inclination and model. Do not over fill - this causes oil to be forced out of the case through the front bearing cover. When adding oil, types and brands of oil should not be mixed because of possible incompatibility.
Operating Temperatures - With Eaton Roadranger CD50 Transmission Fluid Heavy Duty Engine Oil and Mineral Oil The transmission should not be operated consistently at temperatures above 250°F (120°C). However, intermittent operating temperatures to 300°F (149°C) does not harm the transmission. Operating temperatures above 250°F increases the lubricant's oxidation rate and shortens its effective life. When the average operating temperature is above 250°F, the transmission can require more frequent oil changes or external cooling.
The following conditions in any combination can cause operating temperatures of over 250°F:
- operating consistently at slow speeds,
- high ambient temperatures,
- restricted air flow around transmission,
- exhaust system too close to transmission,
- high horsepower, overdrive operation