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high octane and lawn mowers

Before I bought my new car, I'd always fill up my gas can when I filled up my car when the can was getting low. That was when my car used 87 octane.
<br/> Now that my new car uses 91+, how would the little Briggs and Stratten engine handle the higher octane? Will it be alright, or should I make a separate transaction when I fill up my car and get 87 for the gas can? No way will I run 87 in my car, either.


  • edited March 2011
    I really don't see a problem. An engines ability to handle a higher octane means it's less likely to suffer from pre-ignition when using it. In small air cooled 4 strokes this could happen anytime which would mean IMO, you may be better off. You'll notice an increase in power only if you could adjust the timing to take advantage of it. Otherwise, you should notice no difference or a slight improvement in performance IMO, if the motor was designated for 87 octane use. Air cooled motors seem to be so variable in temperature, you have much less control over pre-ignition then water cooled.
  • edited March 2011
    Thanks for not "cheaping out" on your car. We read WAY too many posts asking if it's OK to use regular in "premium" cars.

    The higher octane will not do any harm, but it sure is a waste of money using 91 octane gas in a lawn mower. Please note, the higher octane also will not do the lawnmower any good. It won't run better on 91.

    I suggest the inconvenience of a separate transaction might be worth it. Why waste money on a lawnmower?

  • edited March 2011
    The advantage of NOT separating, is occasionally throwing the unused gas back into the car before winter storage instead of throwing it away or trying to store it too long. The biggest enemy these 4 stroke carb. lawn mower engines have is bad gas. Keeping every thing 91could make it less likely to happen.
  • edited March 2011
    You can do what I do, going hybrid. I have a gas burning car and an electric mower:)
  • edited March 2011
    I have a diesel car and battery powered mower. The motor cycle is gasoline. ?
  • edited March 2011
    Agreed, excessive octane rating does the engine no harm, no good either. It's just wasted money but how much gas does a lawn mower burn annually anyway? I always drained a little gas out of my motorcycle tank to fill the mower because if I bought a gallon can of gas just for the mower, it would go stale before I used it all.
  • edited March 2011
    I had a colleague who owned a VW van--air cooled four cylinder engine. He bought the Clark gasoline we used to have in the area--all gasoline was premium at a regular price. He had to have valve work done because of some burned valves and the mechanic claimed that it was due to the high octane gasoline in an air cooled and that he wouldn't have burned the valves with low octane gasoline.
    I thought that this was bull, so, in the interest of science, I ran my lawnmower on high octane gasoline (I also thought I wanted to get a new mower that was self propelled). Well, the engine still runs and I have had the lawnmower since 1988. Even though Ben Franklin says "A penny saved is a penny earned", I don't think over the summer season that you will go bankrupt using premium in your lawnmower. The lawnmower doesn't really need premium, but if it is convenient, that is what I would do.
  • edited March 2011
    I agree. You get better chance of burning valves with pre ignition from too low octane gas. Why people think higher octane is more volatile, if that's what the implication is, then We're both missing something.
  • edited March 2011
    I know mine doesn't use much. Maybe a gallon a year, depending on how often I mow. I have a 2 gallon can and I don't think I had to fill it up but once last year.
    So a whopping 40 cents difference if I kept with the 93 octane.
  • edited March 2011
    I have a decent sized yard, and I don't think I have an extension cord long enough to have an electric mower. I could almost get away with buying a riding mower for the size of my yard, but the push mower works OK; takes about an hour to do it that way.

    Which reminds me, I should probably get a bottle of oil and change the oil in the mower before I start using it for the season.
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