Synthetic Oil
Myths and Lies
Synthetics and your Warranty
The "W" in 20W-50

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Mild Bill (Asshole #27)
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While there's a lot of claims and speculation about advantages to Synthetic Oils, most are really hard to substantiate. Part of the claims might be true, but it isn't because the oils are synthetic, they're just really well formulated. This is a partial listing of generic advantages to using a synthetic oil over conventional dino oil:

High temperature durability
Lower rate of oxidation
Less ash and sludge
Synths maintain their lubricating qualities longer

The important advantages are high temperature durability and synthetic oils maintaining their lubricating qualities longer.

High Temperature Durability
TC88s heat their oil more. Spraying a jet of oil on the piston skirts cools the pistons down, but heats the oil. Heat eventually breaks down the molecular integrity of all oils, but the more deliberate and deliberate molecular construction of synthetic oils allows them to withstand an extra hundred degrees Fahrenheit over conventional dino oils before experiencing the same loss of lubricating quality. The hotter your oil gets, the more you benefit from using a decent full synthetic.

Synths Maintain Their Lubricating Qualities Longer
Most synthetic oil manufacturers justify the higher cost of synthetics by claiming that you can change your oil at extended intervals. What that claim means is that the oil maintains its lubricating qualities longer.

Look at it this way. Conventional oils break down during normal use and lose their lubricating functionality as the miles pour on. They lose their functionality through oxididation, they build up cooked oil byproducts like sludge, and their inconsistent molecules sheer more easily. When an oil loses lubricating functionality, metal is wearing out metal. Which is hastening the day when you have to rebuild your top and bottom end. What you want is oil that is lubricating just as well when you take it out, as when you put it in.

Well, such an oil doesn't exist. But a synthetic which can be used with an extended oil change interval is sure to be working a lot better if you change it at the normal oil change interval like 2,500-3000 miles (or sooner if you really want to be conservative).

OK, So What Does All This Add Up To
What all this means is that you can hope to extend the life of your engine. How much? Could be 20,000 miles if you're riding in mild temperatures (because a conventional oil lasts longer and works better with ambient temperatures between 50 and 75 degrees F) or 50,000 extra miles if you're riding in hot temperatures (because a conventional oil breaks down and loses quality with hotter ambient, and therefore running, temperatures). Maybe more. There are a lot of variables that affect how long an engine will last, and similar gains can be achieved with conventional oils that are changed much more frequently than required in the service manual.

One of the symptoms of wear is whether your bike uses oil between changes. Some people who started and continued to use synthetic oils by the first 5,000 miles claim that even at 30,000-50,000 miles, their bikes don't use oil between changes (they're taking the same amount out that they put in). This is only empiracle evidence that's really hard to verify, but if the claim is true it would substantiate the lower wear claim for synthetics.