One day long ago someone decided to pour a quart of motor oil into a tank of gasoline and voila the 2-stroke engine was born.

OK, so it didn't exactly work out that way but if you ride a 2-stroke dirt bike or ATV, or operate 2-stroke machines around the house like a chain saw or lawnmower than you know a little something about the unique needs of a 2-stroke engine.

It is true that 2-strokes require what's called premix which is a mixture of gasoline and oil. The oil acts as a lubricant in the engine and burns off with the fuel as you ride. It's easy to prepare as you pour the recommended amount of 2-stroke oil (measured by a ratio like 30-to-1) into a container of regular gasoline, mix it around then pour it into your dirt bike's fuel tank.

We've covered What Gas to Use in Your Dirt Bike or ATV so read that if you're undecided on what actual gasoline to mix with your 2-stroke oil. Hint: Regular 87 octane gas from the local service station works just fine.

As for the best 2-stroke oil it's a bit more complicated because you can't just pour some 5w-30 into your fuel jug.

Four types of 2-stroke oil exist:

  • Petroleum based
  • Castor/Ester based
  • Synthetic
  • Castor/Synthetic blend

Petroleum-based 2-stroke oil

Petroleum based 2-stroke oil is not widely used anymore, if at all, at least in dirt bike engines. We don't sell the straight stuff because we recommend the castor, synthetic or blends. Petroleum based 2-stroke oil is made out of the same stuff you're mixing it with! Thus, 100 percent petroleum based premix oil tends to "become one" if you will with the gas reducing or eliminating any lubricating value.

Some manufactures solve this problem by blending petroleum with castor and/or synthetic oil. So you get a super blend, of sorts. The Maxima Super M goes this route and is a great choice for petroleum-based adherents. Spectro Golden Semi-Synthetic blends petroleum and synthetic. Yamalube 2R is popular with Yamaha riders but can be used in competitor's engines.

Castor-based 2-Stroke Oil

Castor oil use as a lubricant in engines precedes the 2-stroke brapping machine. It remains widely used today and if you're old school you've probably been using the same brand for years. Castor oil is a favorite because it does not burn in the combustion chamber like other oils if you're running too lean. Therefore, if the engine gets too hot, the castor still provides protection.

Additionally, castor oil creates a film that actually benefits vital engine parts especially on a cold start and also acts as a rust inhibitor. It's this film however that posed a problem when the power valve got popular. It gummed up. As a result, pure castor oil has fallen out of favor especially with new riders.

Devotees use Klotz Benol Castor Oil which is degummed to help solve the clogging problem while still providing maximum protection for hot engines.

Synthetic 2-Stroke Oil

Synthetic oils provide excellent lubrication properties and many new cars require the use of synthetic engine oil. Unlike castor oil, synthetics run clean hence their popularity with the power valve. It's a great lubricant especially in the small confines of a 2-stroke engine but as noted before, running the engine too lean burns non-castor based oil in the combustion chamber leaving you without any protection.

Synthetic is excellent oil for the persnickety type because their attention to detail generally prevents a lean running engine.

The Pro Honda 2-Stroke Racing Oil is 100 percent synthetic and despite the manufacturer's name, lots of riders on rival bikes use this oil in their machines. Klotz also makes a pure synthetic formula riders know by smell.

Castor/Synthetic Blend 2-Stroke Oil

Enter the 2-stroke best seller. If castor oil employs a benefit that synthetic doesn't and vice versa why not combine the two? Well, someone did and today the most popular 2-stroke oil is a blend of castor and synthetic. It doesn't gum up the power valve and if the engine overheats, the castor offers the protection synthetics can't.

Maxima Castor 927 uses a highly refined castor oil combined with synthetic oil that address the gumming problem while also retaining the lubrication properties if an engine gets hot. It's one of our best sellers.

In summary:

  • A petroleum based 2-stroke oil fell out of favor long ago because it mixes with gasoline too well.
  • The castor based 2-stroke is a great option because it provides protection if an engine overheats but at the cost of potentially gumming up the valves.
  • Synthetic oil offers the highest lubrication properties available but you risk total engine burn-out if you run the machine too lean.
  • A synthetic/castor blend combines the best of castor and synthetic to cover all your bases.

As with most oils and fluids, it comes down to personal preference, quite often brand loyalty and most importantly what works best in your bike. MotoSport.com sells a comprehensive selection of 2-Stroke premix oils for dirt bikes and ATVs.

Written By: AndrewT