Synthetic vs. Regular Oils
Anthony 'Dezmo' Cappadonna
dezmo@dezmo.com
As a motorcycle mechanic, probably 95% of the maintenance questions I'm asked by owners concerns oil, and what type they should use. More often than not, they want to know if there is any advantage to using a synthetic or 'synth' oil. My answers vary, usually depending on what type of machine is being used and the age/condition of the engine. Hopefully this will help you understand more about this much-debated subject.
The 1st thing everyone wants to know is "Whats Different?" They need some justification to plunk down upwards of $10-15 per quart for synth when 'jim-bobs wunderloob' at the other end of the shelf is only 88 cents. While distrusting non-reputable brands is a given, even the name brand stuff is cheaper, so what gives? Its not so simple, and a minor lesson in the molecular construction of oil is in order:
Conventional oil is refined from crude oil, which is broken down to produce a wide range of petroleum products, from tar for our roads to high octane gasoline...very little of the base crude oil winds up in the bottle on your dealers shelves, and what does wind up there often contains impurities such as sulphur and waxes, which can break down once exposed to the heat and stress of an engine, producing less than desirable lubricating. Granted these impurities are very small in percentage, and do little damage, but it happens. The major percentage of liquid in a typical oil bottle are actually chains of carbon atoms of widely varying lengths. There is an ideal length, but refining simply isnt good enough to produce uniform-length chains, so you get some good ones, along with a lot of chains that are too short and simply vaporize the minute they contact a hot motor part, along with a lot of them that are too long and make the oil thicker, which can rob power from the engine and cause bearing failures. Good, but not great.
Synth oil, on the other hand, is a chemical soup produced from two major components: polyalphaolefins (PAOs), and Esters, along with a few wear additives which vary from brand to brand. PAOs are chemically knitted chains of ethylene much like the carbon chains of regular oil, but these chains can be produced all the same ideal length, creating 'perfect' oil. add some esters (which are themselves excellent lubricants) and youve got an oil that blows anything that began as crude oil out of the water, as far as lubrication qualities go. Zero impurities, less thinning under high heat, and vice versa less thickening when cold. This was actually the goal of the research that led to the development of synth oils, consistent lubrication over a wide heat range. But, the process (not to mention decades of research) is expensive, and the consumer bears the brunt, but they also benefit from it.
"So" you're thinking, "theres no reason I shouldn't use synth." I wish it was simple as that, but there are times where a synthetic oil isn't the best choice. One situation I would never use synth in is new engine break-in. Hard to believe, but they lubricate TOO good. Motor builders have reported rings not being seated even after several hours of dyno break-in time. This isnt a new problem, engine manufacturers had the same problem back in the 40s and 50s when petroleum-based oils became more widely used than the castor oils in use before that. Eventually metallurgy caught up, and engines could be broken in on 'petro' oils, but this level has not yet been reached for synth. I recommend at least 1500 miles on new motors before switching to synth if desired. There is no harm in mixing synth/reg oil or switching between them for oil changes. One other place I dont recommend synth is extreme high-mileage engines. The tolerances are usually much looser than new, and a oil more prone to thickening is desirable.
I'd like to add something else about motorcycles and oil in general. Most bikes lubricate their transmissions with the same oil supply as the engine. While there is nothing wrong with this, it does mean a harder life for your oil than your typical car engine. All those gears are great for shearing oil chains, and most motorcycle-specific oils are designed to combat this. Car oils are not. I'm not saying your motorcycle will blow up or seize if you use car oil, but it will wear out quicker, and provide less lubrication in the process. Also, many car oils have detergent additives, which makes the 'wet' clutches of most bikes slip. It wont be a sudden failure, but eventually it will slip...the only way to fix this is new bike-specific oil, and new clutch plates. Dont say I didnt warn you. Also, there are a lot of aftermarket oil additives out there that claim wondrous results from adding them to your oil. Dont believe the hype, they are nothing but more of the same detergent and wear additives car oils are already full of. As Gordon Jennings once said concerning additives: "This stuff reduces the friction in your wallet enough to make money slip out of it, but may not do anything else." Wise words indeed...stay away from additives.
So it really is up to you (and your wallet) as to whether or not you should use synth. But when you think about it, oil is oil, and even the cheap stuff will lube a motor, if not as good. Personally I find Mobil 1 (who isnt paying me a dime to say so) is the best oil on the planet, and nothing else coats the internals of my bikes. Its one of the most expensive, but the company pioneered most of the research that led to synth, and they know best.
For an even more informative, and much more detailed article about oil in general, check out the Gordon Jennings article quoted above.