Charon
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Re: Oil temps and usage comparison
Reply #206 - 10/27/10 at 15:23:53
The whole "oil test" idea has been nagging at me, so today I went out and ran a "proof-of-concept" preliminary test, using my generator. I must stand corrected, though - I said it was a 2500 watt unit, but it is only 2400 watts. I mounted the little one-quart tank using cable ties, and ran a clear fuel line to the carburetor (this engine has a carburetor separate from the fuel tank, with a needle and float in it). I made a wire pointer and attached it to the throttle on the carburetor, then stuck a piece of tape to a convenient spot so I could see how far open the throttle actually is. I filled the tank, started the engine, and plugged a voltmeter into the outlet. 133 volts, unloaded. I marked the throttle position on the tape, then plugged in a 1000 watt heater. Voltage dropped to 125 volts; throttle opened up some, and I marked its new spot. I unplugged the 1000 watt heater and plugged in a different one, unmarked for power. Voltage dropped to 123 volts; throttle opened slightly more than with 1000 watts. I marked that spot, too. Then I added the 1000 watt. Voltage dropped to 110 volts; throttle opened some more (but not quite to the wide-open mark I had previously made). I marked the spot. Somewhere in there I remembered to start a stop watch, but wasn't too worried about exact timing for the trial run. I walked away for about five minutes (noisy darn thing), and when I came back noticed the throttle had closed a little. Voltage was still 110 volts. My guess is that the engine and its oil warmed up during that time.
Under the full load the engine ran for right at 30 minutes. I had calculated it ought to run for somewhere in the 30 - 35 minute range, so was glad to see my calculations verified. I have not yet installed any temperature measuring stuff, but I am still strongly thinking about drilling the oil-fill plug and sticking a meat thermometer through it into the oil. I am also going to refine the throttle position indicator, and find a way to measure current.
The engine presently has 10W-30 oil in it, but I didn't write down what brand when I changed it last. I'll make my refinements, and run another test or two to see if things are reasonably repeatable. I have on hand both Rotella 15W-40 conventional and Rotella 5W-40 synthetic oils, so they will probably be the first ones tested. I also have some 5W-30, so it will likely be tried too.
I am thinking about the cross-contamination issue. When I drain one oil, some will stay in the engine to contaminate the next oil. I think I may keep the 10W-30. Then when I drain a test oil, I'll put the 10W-30 back in, run the engine for a few minutes, and drain. That way at least the cross-contamination will be more or less the same.
Anyone have any suggestions (that don't cost a lot of money, since I am retired and there was no COLA either last year or this)?
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