I suggest 5W30 Mobil 1. It has all the characteristics of a straight
weight 30 conventional except it doesn't get as thick when cold, can
stand a lot higher temperatures and has little or no viscosity
improvers. The worst part of conventional multi grade is that it
contains lots of Viscosity Improvers. It can be bad news for a hot
Amzoil ad but says the same thing:
See the section titled:
WHAT ABOUT ENGINES THAT REQUIRE A STRAIGHT WEIGHT OIL?
I run Rotella 5w 40 synthetic in everything. It a diesel rated
synthetic that tests out better than Mobil 1 at a better price. I have
a lot of engines and needed something that would work in all of them. I
use it in everything form the 4 stroke weed wacker to the backhoe.
Single grade used to be cheaper, most places you
can even find it. You don't need anything better.
than a good multigrade. I think using single
grade is a big myth just using non detergent oil.
My lawnmower motors last till everything else
falls apart. I have used multigrade for a long
time (at least 10W-30 and 10W-40 is probably
better. Change the oil at least once a season,
two times is better, and at least every 25 hours.
Clean the air filter at least every season and
adjust the carb correctly as needed, about 1/2 way
between rpm fall off at two rich and two lean; too
lean burns valves so stay toward rich side.
Biggest point is having the engine full of oil and
keeping the oil clean.
Most lawn equipment wont be operated below 32f maybe many manufacturers
therefor don't recommend or see the need for multigrade where cold
starting benefits from lower oil weight. Synthetics are proven to
reduce wear, something many small engines need because of poor design.
My generator recommends synthetic. Many small cheap motors only have a
design life of 250-350 hours, commercial users need more and do benefit
Another thought that occurs to me. Small engines, like lawn mowers, don't
have oil pumps and therefore you don't have bearings that are pressure
lubricated. They don't have the tight clearances that bigger engines have,
and therefore using a straight 30w probably doesn't hurt anything. In a
bigger engine, if you switch to a thicker oil, tight clearences that were
lubricated with the thinner oil might not be lubricated with the heavier
oil, and will wear. You go back to a thinner oil and you might experience
oil consumption. This is what they taught in internal combustion engine
class I took many years ago - not sure if anyone has actually proved this in
the field or not.
So, any general consensus? Stick with a straight 30 synthetic and don't
worry about it?
For that, no argument here!! I didn't catch what level of JD it was.
Guess even their pushers (if they even make those) are decent.
Don't need the warranty being argued because it's claimed the customer
used inferior oil. I'd even keep the oil receipts!
Because that is a remnant of the pre-synthetic days. Standard
multi-grade oils don't perform well in an air cooled small motor. They tend
to break down and end up as 10W and worse. Synthetic oils however can
handle the heat and should be fine.
Thanks for the question, because it is time for an oil change on my
mower and I believe I am out of 30W but I have good synthetic around. I
will switch. I just had not thought of it.
Because single weight is cheaper and the manufacturer doesn't think
synthetics or multiweights are necessary. If you use them, they won't
hurt anything but your pocketbook.
You're not going to run either machine in sub-freezing temps or go for
You might check out the website of the engine manufacturer, perhaps
Tecumseh or Briggs & Stratton, (as opposed to the lawn motor/tiller
manufacturer) for more info.
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