1972 grasshopper with 18hp vanguard engine. How do I remove the sludge so I can change oil? Drain plug out I added oil to see if fresh would run through will not. It’s bad almost like grease. Any thought would be great thanks. I was thinking of spraying gasoline up through the drain plug to try and loosen and break up the sludge.


I think you might have better luck with a bottle brush soaked in kerosene.

As silly as it might sound, snoop around the kitchen area of a place like Bed Bath and Beyond. Once you have flow, I would use a commercial oil flush solvent, or the same kerosene in a pinch - no more than 30% of the total oil capacity. Run that at idle until hot, drain, and possibly repeat.

Finally nothing but fresh oil. I suggest Shell Rotella or a similar diesel oil that has a high detergency.

The good news is that 18hp Vangaurd is a beast and will withstand a lot of abuse. 47 years is not a bad run, and if you clean it up it may last another four decades.

  • Thanks steve, I’m gonn a give that a try. Hopefully your your right and the engine is a beast.
    – Frank
    Jul 23 '19 at 13:14
  • 1
    Upvote for Kerosene. A friend of mine uses a mixture of petrol and diesel (which he only has as the result of a mis-fueling) and in the past I've known people use diesel but kerosene is probably logically the best stuff to use. Jul 23 '19 at 15:16

First I wouldn't not spray gasoline in the engine.

Add one quart of engine sludge remover. Start up the engine and warm it up. Monitor the oil light. If at any point oil light comes on, turn off engine immediately.

After running the engine at idle for about 20-30 min, remove the drain plug and drain the oil.

I would do a few frequent oil changes with fresh oil and sludge remover blended in to get rid of the sludge. Also make sure to replace the filter with each oil change.

Be very careful as your engine is a high risk of overheating and seizing.

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