Yea, I know, shame on me.
How do I clean the oil compartment if the oil is all burnt?

Here's what happened:
My mower started smoking and it occurred to me that I haven't changed the oil in a year. Checked the dipstick and sure enough it was pretty low.

I'll be making a trip to get some oil, but how do I get the old stuff out there? I'm not asking how to do an oil change, but rather should I try to clean the old stuff out there first? this is assuming there's not much oil left to siphon/pour out.

I can only think of two ways:

  • just pour the new one in and pray that it will keep on running till the manufacturer recommended oil change
  • pour new oil in and give it a small run (half an hour of mowing), hope the old oil gets diluted in the mean time and then do a real oil change?
  • 1
    Ditch it and get a reel mower. :) – iLikeDirt Jun 12 '15 at 2:15
  • @iLikeDirt what's a reel mower? does it turn grass into yarn or something? or do you mean the scottish folk dance? am i supposed to trample the ground by dancing? :P – ton.yeung Jun 12 '15 at 3:13
  • It's a manual mower. No engine to baby. – iLikeDirt Jun 12 '15 at 4:16
  • If his yard is small, I agree that a motorless reel mower is the way to go. I switched to one when I lived in a hot climate and wanted to cut the grass early in the morning before it got too warm (too early to power up a loud lawnmower - the reel mower was nearly silent). My yard wasn't that big - around 40 ft by 60 ft and the reel mower worked well as long as I didn't let the grass get too high. But since he has a self-propelled mower, I'm guessing that his yard is not small. – Johnny Jun 12 '15 at 5:02
  • @iLikeDirt oh so a reel mower is a real mower :D learned something new. – ton.yeung Jun 12 '15 at 6:03

I doubt that your real problem is burnt oil sitting in the engine - the most likely way for oil to be burnt and causing smoke in the exhaust is if the rings are bad and/or the cylinder is scored (possibly because of running too long without enough oil).

You can get a good sense of whether your engine is burning oil by checking the spark plug and looking for deposits or other fouling.

If you're really worried about the oil (i.e. if it's extremely dirty or diluted), change the oil (don't just top it off), then run the engine long enough to warm it up, then change it again.

If the engine doesn't run well with new oil, an engine overhaul is probably your best bet (and usually not that hard to do with a single cylinder small engine if you can find an overhaul kit for it). If the cylinder is scored you might be able to have it bored if you can find an oversize piston and/or rings.

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  • I agree with filling the oil and then changing it soon thereafter. If there is a more serious problem caused by very low oil, running the engine for a few minutes isn't really going to change anything. However, the engine rebuild may or may not be worthwhile. The kits can be $80+ just for the parts, plus you will need an assortment of tools. If this were me and flushing the oil didn't help, I would just cut my losses. – Hank Jun 12 '15 at 4:56
  • I'll try this and see what happens, if it doesn't work i just learned a pricey lesson in mower maintenance. – ton.yeung Jun 12 '15 at 6:06

You could either get some "motor flush" (oil change pre-treatment) at the auto parts store, or some diesel or kerosene at the fuel pump (more or less the same thing) and add it to the gunk you have now, crank it around a few times (don't run it, as you'll have a much higher percentage of that stuff in there than normal), perhaps let it sit overnight, stir it up again, drain, and then refill with (inexpensive) oil, and change that after another 5-10 hours use if the motor does not seem to be hopelessly damaged.

Make yourself a pre-mow checklist that includes checking the oil. And a fall "when mowing stops" checklist that includes changing it then.

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  • I'll probably change the oil periodically anyway, in addition to checking the oil every time. – ton.yeung Jun 12 '15 at 15:23

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