I have two lawn machines that are two-cycle. One calls for a 50.1 mix and
the other calls for a 40.1 mix.
How important is it to maintain these exact dilutions.
What harm will be caused by using a 50.1 mix in a machine calling for a 40.1
mix, or a 40.1 mix in a machine requiring a 50.1 mix?
I think the ratios are "close enough for goverment work" so that it really
doesn't make much difference.
What's important though is to use a two cycle oil that's formulated
specifically for small *air cooled* engines-- not the stuff rated TC-W3
readily available most anywhere which is designed for watercooled engines
like outboard motors on a boat. Water cooled applications are a lot less
In years past, it didn't use to make much difference- most any 2 cycle oild
would do-- but with the newer lawn equipment engines running hotter and
leaner, you really should use the stuff formulated for them. And of course,
it's much more expensive!
"This is my keyboard. There are many like it, but this one is mine."
The ratio is more a function of oil technology than engine technology.
You could use either ratio but my preference would be the 40:1 ratio
for both. Use fresh premium fuel and oil from a major manufacturer
like Echo, Stihl, or Husquvarna.
I just started using Mobil 1 synthetic MX2P. (Autozone sells it)
These engines are designed for these mixes. Too little oil and you burn up
the engine sooner, too much oil and you would tend to foul plugs, at
minimum. Do yourself a favor, two gas cans, mark them and keep the oil mixes
per manufacturers spec.
Same with weed trimmers, chain saws, etc. use what the manufacturer
I have seen some two cycle oil that touts itself to work in all different
engines with the same mix, but I don't trust it.
Technology and oils have changed. I'd agree with a 50:1 and a 16:1, but the
difference between 40 and 50 is minimal. The new oils allow for a lesser
concentration. On my Stihl saw, they give 40:1 for normal oil, but 50:1 for
their branded synthetic oil.
I've been using one mix for a few years with no problems.
I take 2 8oz cans of lawnboy oil and put it in a 5gal gas can, and then
fill it up at the pump and work the nozzle all around the can as I am
filling it to get a good mix. That way after the mowing season I use it for
my snow blower. I also use this gas for my weed whacker, chain saw, and
small tiller. I've never had a problem.
I've had no problem for 25 yrs using synthetic 50:1 in a wide variety
of 2-strokes, which routinely get worked _hard_. Put simply, more oil
than required means more smoke and more deposits in port and muffler.
And by all indications, the better 50:1 covers it.
Then you can concentrate on having one gas can with oil mixed in, and
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