# Lawnmower EMERGENCY! Please Help! **URL:** \ **Category:** Factual Questions\ **Created:** [May 14, 2003, 7:11pm UTC](https://boards.straightdope.com/t/lawnmower-emergency-please-help/175266 "2003-05-14T19:11:40Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![McLeo](https://avatars.discourse-cdn.com/v4/letter/m/91b2a8/32.png) [@McLeo](https://boards.straightdope.com/u/McLeo)\ **Post date:** [May 14, 2003, 7:11pm UTC](https://boards.straightdope.com/t/lawnmower-emergency-please-help/175266/1 "2003-05-14T19:11:40Z")
Well yesterday my dad had ordered me out to the yard to mow the lawn for the first time this year. Being the smart guy my dad is, he fills up the fuel, where the motor oil is supposed to go!!! Without me knowing, I tried to start the mower by pulling the cord, and luckily, there were no explosions. Now we have to drain out all the fuel from the oil tank. My question is, if we drained out all the oil and left the cap on for a few days, letting it dry out, then filling it back up with oil this time, would the mower be fine? Would I be expecting iminent death from explosion the moment I start the mower? Or should I bring it to a repair guy to see if it’s alright? Thanks. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [May 14, 2003, 7:22pm UTC](https://boards.straightdope.com/t/lawnmower-emergency-please-help/175266/2 "2003-05-14T19:22:54Z")
Yeah, it should be fine. Even just an oil change without letting it air out should be ok. ---
**Author:** ![jayfarns](https://avatars.discourse-cdn.com/v4/letter/j/e274bd/32.png) [@jayfarns](https://boards.straightdope.com/u/jayfarns)\ **Post date:** [May 14, 2003, 7:25pm UTC](https://boards.straightdope.com/t/lawnmower-emergency-please-help/175266/3 "2003-05-14T19:25:44Z")
Jusy empty the fuel, and refill with 30W oil. Should work just fine. ---
**Author:** ![casdave](https://avatars.discourse-cdn.com/v4/letter/c/c6cbf5/32.png) [@casdave](https://boards.straightdope.com/u/casdave)\ **Post date:** [May 14, 2003, 7:32pm UTC](https://boards.straightdope.com/t/lawnmower-emergency-please-help/175266/4 "2003-05-14T19:32:35Z")
I should get some oil into it soonest, the petrol might damage some of the seals. Put some oil in and flush it, then fill up again. With luck there was already oil in there when it was topped up with fuel and this should reduce any ill effects. You don’t mention wether it is a 2-stroke, but if it is then it should be fine, after all the oil and fuel are mixed together in metered amounts anyway. If it is a 4 stroke, it depends on it it ran for any length of time, if it did then lack of proper lubrication to the main bearings might have caused damage, and then its strip down and rebuild time. I don’t think it would be a good idea to leave the engine dry out from the fuel, as the oil that should have been there also prevents surface rust, if you live somewhere humid and warm it might from a very small amount, which may not hurt it too much, but its best to be wise. ---
**Author:** ![casdave](https://avatars.discourse-cdn.com/v4/letter/c/c6cbf5/32.png) [@casdave](https://boards.straightdope.com/u/casdave)\ **Post date:** [May 14, 2003, 7:41pm UTC](https://boards.straightdope.com/t/lawnmower-emergency-please-help/175266/5 "2003-05-14T19:41:08Z")
I should get some oil into it soonest, the petrol might damage some of the seals. Put some oil in and flush it, then fill up again. With luck there was already oil in there when it was topped up with fuel and this should reduce any ill effects. You don’t mention wether it is a 2-stroke, but if it is then it should be fine, after all the oil and fuel are mixed together in metered amounts anyway. If it is a 4 stroke, it depends on it it ran for any length of time, if it did then lack of proper lubrication to the main bearings might have caused damage, and then its strip down and rebuild time. I don’t think it would be a good idea to leave the engine dry out from the fuel, as the oil that should have been there also prevents surface rust, if you live somewhere humid and warm it might from a very small amount, which may not hurt it too much, but its best to be wise. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [May 14, 2003, 8:03pm UTC](https://boards.straightdope.com/t/lawnmower-emergency-please-help/175266/6 "2003-05-14T20:03:29Z")
It’s probably fine. Here’s what I would recommend. It may be a little bit overkill, but it will only cost you a few bucks in oil: 1. Remove oil filler cap and oil drain plug and allow to dry out overnight (as you mentioned). 2. Reinstall oil drain plug. 3. Disconnect spark plug cable from spark plug. 4. Fill with oil. 5. Turn engine over by hand about a dozen times. Pull as hard as you can. 6. Drain and discard oil. 7. Fill with new oil. 8. Reconnect spark plug cable. 9. Start and run engine for 1 minute. 10. Drain and discard oil. 11. Fill with new oil. You’re ready to go. ---
**Author:** ![billy](https://avatars.discourse-cdn.com/v4/letter/b/ecd19e/32.png) [@billy](https://boards.straightdope.com/u/billy)\ **Post date:** [May 14, 2003, 11:17pm UTC](https://boards.straightdope.com/t/lawnmower-emergency-please-help/175266/7 "2003-05-14T23:17:12Z")
> [@](#): > > _Originally posted by Crafter\_Man \* > \*\* It may be a little bit overkill_\* No, it’s absolutely overkill. They are both petrol products, it’s not that big of a deal. Drain fuel and oil mixture, refill with oil, and you’re done. You need a controlled amount of properly mixed gas and air to get the Hollywood styled explosions. Even if there is a residual amount of gas in the crankcase after changing oil, it will likely burn off as the oil heats up. It’s not like oil won’t burn anyways. ---
**Author:** ![McLeo](https://avatars.discourse-cdn.com/v4/letter/m/91b2a8/32.png) [@McLeo](https://boards.straightdope.com/u/McLeo)\ **Post date:** [May 15, 2003, 12:37am UTC](https://boards.straightdope.com/t/lawnmower-emergency-please-help/175266/8 "2003-05-15T00:37:26Z")
Hmmmm… thanks for all the responses guys. I drained out the stuff and filled it up with oil. Going to let it sit overnight to let the oil do its thing, and hopefully it would run fine tomorrow! Thanks again!