A Little Pump Makes a Big Difference

Adding oil to an Onan generator at the end of an oil change can be excruciatingly slow. The process involves adding an ounce at a time with a frustrating pause in between. Holding the bottle is awkward due to poor access, and pouring the oil in directly from the bottle leads to small spills. I solved the problem by using a gear lube pump, which I normally use to add oil to the lower unit of my boat’s outboard motor. I bought it at Walmart for about $5. Place one end in the oil bottle, and the other in the oil port on the generator. Then slowly work the plunger to add oil in the recommended amounts. Note: Some oil bottles have different size caps and won’t accept the screw-on cap of the gear lube pump.

Ken Dwiggins | Reno, Nevada


 

4 COMMENTS

  1. Thank you, that’s a great solution to a messy problem. Hurry and patent it before Onan does. In fact, get ahold Of a plastics company and work a deal for manufacturing a pump action with universal cap system with your name on it. I’m all in! Good luck, thanks again. Next job is to come up with an easy engine oil service system for owners like me that struggle servicing the oil in my Ford V-10 Coachman. Coachman either put profit over practical or lacks vision and innovation in their designs. Personally I think all three.

    Bryan

  2. I can never tell for sure how much oil I have in my generator. When you fill it with the ”recommended amount” you get one reading. After running it, it will inevitably be ‘overfull’ on the stick, crazy. I never know how much oil I have in it except right after the oil change, because I KNOW how much I put in. And, when you first check it in the morning, it will have one reading, and then after you put the stick back in, and recheck it, it will be overfull again, within 5 seconds of the first reading! It’s like when you remove the stick, it sucks oil up into the oil dipstick tube. I’m at a loss. It’s an old 7.5 Onan with a 3 clyinder Kubota motor. Runs great, but am dumbfounded on the oil dipstick readings.

    • I have a similar issue with my Generac and this is my routine: When the generator is cool and the RV is on relatively level ground, I remove the dipstick, wipe it clean, and then re-install it. Then I remove it a second time and check the oil level. That second reading is what I consider to be the most accurate reading. It seems my generator will develop crankcase pressure, either positive or negative, that affects the oil level after it’s shut down and removing the dipstick the first time bleeds off trapped air pressure. Also, if your Onan has an automotive type spin-on oil filter, I believe the brand/type of filter you use can influence the oil level as well, especially when you are dealing with the small oil capacity of an RV generator. With the procedure you described, it sounds to me like your generator oil level is slightly high. Motor oils have tackier surface tensions too, and they tend to “cling” to surfaces differently than other fluids which may also be influencing your dipstick readings. Hope that helps!

  3. Dennis,
    I have a similar issue with my Generac and this is my routine: When the generator is cool and the RV is on relatively level ground, I remove the dipstick, wipe it clean, and then re-install it. Then I remove it a second time and check the oil level. That second reading is what I consider to be the most accurate reading. It seems my generator will develop crankcase pressure, either positive or negative, that affects the oil level after it’s shut down and removing the dipstick the first time bleeds off trapped air pressure. Also, if your Onan has an automotive type spin-on oil filter, I believe the brand/type of filter you use can influence the oil level as well, especially when you are dealing with the small oil capacity of an RV generator. With the procedure you described, it sounds to me like your generator oil level is slightly high. Motor oils have tackier surface tensions too, and they tend to “cling” to surfaces differently than other fluids which may also be influencing your dipstick readings. Hope that helps!

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