2/2/00
Updated 2/19/02

Two Cycle Oil for Outdoor Power Equipment

Seems there is some confusion these days as to what oil should be used in todays outdoor power equipment with 2 cycle engines. I'll try to explain it as simply as I can. I'm not a chemist so I can't go into specific formulation detail of how that formulation works, it probably wouldn't make any more sense to you then it would to me. Just the basics are all that are needed.

You're going to see ratings on oil and one of the common ones is B.I.A. Well, B.I.A. is the boating industries standard and to the best of my knowledge hasn't been substantially upgaded since the 50's. Worse, it is not a air cooled outdoor power equipment oil.

2 cycle oil is deigned to be burned with the fuel as cleanly as possible after having done it's job of lubricating the engine. Water cooled boat motors or liquid cooled motorcycles and atv's run much cooler and a much slower rpm then air cooled outdoor power equipment. Your chain saw or line trimmer need an oil that will not only protect the engine at faster rpm's and higher temps but burn clean in those conditions without coating the piston, rings and cylinder with unburned or half burned goo which will seize it. Likewise, a boat engine may not recieve proper protection from oil formulated for air cooled outdoor power equipment for the same reasons, in reverse.

Todays 2 stroke engines run hotter then ever because they are running leaner then ever to meet emission regs of C.A.R.B. and E.P.A. That's, California Air Resources Board and the Environmental Protection Agency(Feds). Some of the newest engines are "Strato-Charged" engines and more are likely to be on the way.

So what is a "Strato Charged" engine? I'll try to keep it simple. Standard 2 stroke engines fill the combustion chamber with a charge of fuel/oil through the transfer ports from the crankcase. This fresh fuel/oil charge pushes out the burned fuel/oil out the exhaust port. Typically this exchange also blows about 1/3 of the fresh, unburned fuel/oil right out the exhaust port as well. This excess helps considerably to cool the engine but also sends a lot of emissions out the pipe. Without going into the gory details, a Strato Charged engine sends a measured charged of fresh air only into the combustion chamber to blow the exhaust out, followed by the fresh fuel/oil/air mix.

All outdoor power equipment 2 stroke engines should be run on modern 2 stroke oil made for them. Fail to do so will and early engine death is around the corner, fail to do so in a Strato Charged engine and you may not get to the corner.

So what do you look for to assure you are buying oil that will properly protect your outdoor power equipment 2 stroke. There are 2 standards to look for. Both are the same, so you don't need to find both on the label. One is "JASO-FC", this is the Japanese equivelent of the rating. The second, ISO-EGD, is more of a world wide rating. The "C" in the JASO rating and the "D" in the ISO rating are the upgrade figures. Much the same as with automotive motor oil where for example "SD" or "SF" is used. The "F" being a improved grade. So if you buy something other then the equipment makers oil, make sure the ratings for JASO is "FC" or greater, for ISO, "EGD" or greater.

Echo, Husqvarna, Stihl and Red Max have these oils. Others may have them as well, read the label.

Just about every manufacturer has an oil company producing oil with their name on it and to their specifications. While your equipment is under warranty it may be best to use their oil just to cover yourself. If you have multiple brands and don't wish to mix multiple batches of fuel/oil mix, go with Husqvarna, Echo, Stihl or Red Max. These manufacturers have some of the highest output engines on the market today and need the highest level of air cooled engine protecion available and their oils will get the job done in any modern air cooled 2 cycle outdoor power equipment.

So long as you use an oil designed for todays modern 2 cycle air cooled equipment, you shouldn't have an oil related failure. The rest is up to you. Making the proper fuel/oil mix is critical. Most oils today are designed for a 50-1 ratio. One gallon of gas is 128 fluid ozs. That will require 2.56 ozs of two cycle oil, rounding off to 2.5 is a safe bet. Thats not much oil in a gallon of gas so you can maybe better understand the need to use the proper quality oil. Too much will cause plug fouling, carbon build up and partially burned oil that burns into the piston and cylinder causing the engine to overheat. Overheating is one of the major causes of failures in two cycle engines.
Too light on the oil mix will not lubricated properly and again cause, overheating. Overheating causes metal to expand and then you have a seizure.

Old fuel also doesn't burn clean and leaves a burnt residue on the piston and cylinder and results in a very similar condition as too much oil or a boat oil. End result, seizure. 30 days is the limit for fuel before it's too old. Mix no more then a gallon at a time, unless you're a commercial user, and at the end of each month dump what's left into your car when it has a full tank. The dilution of a half gallon of mixed fuel or what ever was left in to your cars full tank isn't going to hurt your car and you'll be able to use up all your fuel without wasteing it. However, if you've got gas that's been sitting for months and smells like something evil, take it to a recycler rather then putting it in your car.

Yes, you may have to come to a shop like the one I work for to get good quality oil as you aren't likely to find it at your gas station or supermarket, but like the old commercial goes; You can pay me now or, uh, you get the message.