timmyboy76
New Member
There are very few subjects that stir the emotions of PWC performance enthusiasts more than to ask, what 2 stroke oil do you use and why? This site has dedicated more ‘bandwidth’ to this subject than just about any other topic. Most of the discussions end up in heated debate with no one really changing anyone else’s mind on what oil is the best anyway. We tend to vehemently defend our choice as if our very reputation depended on it. I sometimes think we are more loyal to our favorite brands of oil than to our favorite brand of ski (hopefully Sea-Doo). Well, maybe we’re not quite that loyal to our oils, but close to it. If it’s any consolation, PWC performance enthusiasts are not the only group of “motorheads” that staunchly defends their choice of oil. I belong to several other performance oriented motorsport discussion groups (Ford-Diesel and Racetech-KTM) and they do it also. With all this said, let’s all take a deep breath and put our emotions and biases in a closet somewhere and try to look at this magic miracle ‘brew’ we call 2-stroke engine oil.
What’s in the stuff anyway?
2-stroke engine oils, like most other engine and gear lubricants, are composed of base oil plus an additive package. The additive package can be as simple (only one or two components) or as complex (multiple components), depending on the requirements of the oil.
Base Oil Types
Base oils compose from 50% to 95% of the total weight of the 2-stroke engine oil. They fall into 2 general categories: synthetic and petroleum based. There is a third category, vegetable, I will discuss later. Since synthetic oils are manufactured from petroleum, there has been a lot of litigation flying around about what really constitutes a ‘true synthetic’ oil in the last several years. There is no universally accepted definition for synthetic oil. Each manufacturer is free to label their product ‘synthetic’ by whatever rules the manufacturer chooses. The API (American Petroleum Institute) has defined base oils into 5 different grades or groups rather than use the terms synthetic and conventional (petroleum). The groups are classified by quality of their VI (viscosity index). The VI is a relative measure of the base oil’s ability to not thicken at low temperatures and not thin out at high temperatures. The higher the VI number, the more resistant the oil to changes in viscosity as its temperature changes. Perfect base oil would have no viscosity change at all with temperature change. Some silicone-based oils have extremely high VI, but, unfortunately, they are terrible metal lubricants, so they can’t be considered for engine lubrication. The higher the API group number, the higher the VI number. Most, if not all, high performance 2-stroke oils are manufactured using API group III and IV and occasionally group V base oils. GroupIII (hydrocracked/hydro-treated petroleum oils) are used in non-synthetic and synthetic blends and Group IV (VHVI and PAO synthetic oils) are used in full synthetic and synthetic blends. Group V (Ester synthetic base oils) is rarely used because of their expense and they do not mix easily with gasoline and they are not compatible with some other oils. There are a number of advantages to using synthetic base oil in addition to the better VI. Synthetics have a much higher flash point than petroleum base oils.
Synthetics will not decompose as easily at high engine temperatures as petroleum. The engine stays cleaner because less varnish deposits on the power valves, ring lands and piston crown. They also transfer heat better than petroleum-based oils. In summary, it’s fair to say synthetic based oils (with the correct additive package) will out perform their petroleum-based cousins at extreme loads/temperatures. I mentioned a third category of base oils earlier, vegetable or Castor (not Castrol, that’s a manufacturer) bean oil. This oil is derived from pressing oil out of castor beans and distilling it. ‘Bean Oil’ as it is often referred to, has some very unique characteristics; some very good, others not so good. The good is that it is an excellent lubricant. It seeks out hot spots in the engine and clings to those hot surfaces much better than petroleum type oils. The bad is that it does not mix with gasoline easily and it burns ‘dirty’ (excessive carbon/varnish deposits). In the early 70s, before power valves were used, castor bean oil was very popular in racing 2-strokes. Now that power valves are common and we have improved petroleum and synthetic oils, castor bean oil is seldom used anymore. Several companies still market it in the form of a degummed castor oil for racing applications only. It should be avoided for recreational use unless you enjoy tearing your engine down for a top end cleanup fairly often. Several manufacturers formulate their oil with castor bean oil as an additive (antiwear agent) rather than base oil. They blend it with their petroleum and synthetic base oils. When castor bean oil burns, it has an unmistakable ‘sweet’ smell.
What’s in the stuff anyway?
2-stroke engine oils, like most other engine and gear lubricants, are composed of base oil plus an additive package. The additive package can be as simple (only one or two components) or as complex (multiple components), depending on the requirements of the oil.
Base Oil Types
Base oils compose from 50% to 95% of the total weight of the 2-stroke engine oil. They fall into 2 general categories: synthetic and petroleum based. There is a third category, vegetable, I will discuss later. Since synthetic oils are manufactured from petroleum, there has been a lot of litigation flying around about what really constitutes a ‘true synthetic’ oil in the last several years. There is no universally accepted definition for synthetic oil. Each manufacturer is free to label their product ‘synthetic’ by whatever rules the manufacturer chooses. The API (American Petroleum Institute) has defined base oils into 5 different grades or groups rather than use the terms synthetic and conventional (petroleum). The groups are classified by quality of their VI (viscosity index). The VI is a relative measure of the base oil’s ability to not thicken at low temperatures and not thin out at high temperatures. The higher the VI number, the more resistant the oil to changes in viscosity as its temperature changes. Perfect base oil would have no viscosity change at all with temperature change. Some silicone-based oils have extremely high VI, but, unfortunately, they are terrible metal lubricants, so they can’t be considered for engine lubrication. The higher the API group number, the higher the VI number. Most, if not all, high performance 2-stroke oils are manufactured using API group III and IV and occasionally group V base oils. GroupIII (hydrocracked/hydro-treated petroleum oils) are used in non-synthetic and synthetic blends and Group IV (VHVI and PAO synthetic oils) are used in full synthetic and synthetic blends. Group V (Ester synthetic base oils) is rarely used because of their expense and they do not mix easily with gasoline and they are not compatible with some other oils. There are a number of advantages to using synthetic base oil in addition to the better VI. Synthetics have a much higher flash point than petroleum base oils.
Synthetics will not decompose as easily at high engine temperatures as petroleum. The engine stays cleaner because less varnish deposits on the power valves, ring lands and piston crown. They also transfer heat better than petroleum-based oils. In summary, it’s fair to say synthetic based oils (with the correct additive package) will out perform their petroleum-based cousins at extreme loads/temperatures. I mentioned a third category of base oils earlier, vegetable or Castor (not Castrol, that’s a manufacturer) bean oil. This oil is derived from pressing oil out of castor beans and distilling it. ‘Bean Oil’ as it is often referred to, has some very unique characteristics; some very good, others not so good. The good is that it is an excellent lubricant. It seeks out hot spots in the engine and clings to those hot surfaces much better than petroleum type oils. The bad is that it does not mix with gasoline easily and it burns ‘dirty’ (excessive carbon/varnish deposits). In the early 70s, before power valves were used, castor bean oil was very popular in racing 2-strokes. Now that power valves are common and we have improved petroleum and synthetic oils, castor bean oil is seldom used anymore. Several companies still market it in the form of a degummed castor oil for racing applications only. It should be avoided for recreational use unless you enjoy tearing your engine down for a top end cleanup fairly often. Several manufacturers formulate their oil with castor bean oil as an additive (antiwear agent) rather than base oil. They blend it with their petroleum and synthetic base oils. When castor bean oil burns, it has an unmistakable ‘sweet’ smell.