Reprinted from Motocross Action Magazine - August 1998
Last year it was a rarity to hear a four-stroke motor at your local track. Now, it seems like there is always a Yamaha YZ400 breathing down your neck (even if it is three turns behind you). The amazing success of the YZ400 is, however, only the beginning of the quad-stroke invasion. There will be YZ400 challengers from the other Japanese manufacturers, plus all-new entries like the Cannondale. This is great news for any self-respecting motorhead, but there is a learning curve to this shift in motocross engine preference. Four-strokes are different from two-strokes in a lot of ways, not the least of which is the demand they put on motor oil. The MXA wrecking crew asked Maxima's Dick Lechien to give us the full skinny (or should that be full slimy?) on four-stroke lubricants.
THE WRONG STUFF
MXA: Street-bike riders have used automotive oils for years. Why can't we?
Dick: Automotive oils have taken a turn for the worse in relationship to motorcycles. The Environmental Protection Agency (EPA) got involved with lubrication just after it got involved with clean air gas blends.
MXA:Is the U.S. government involved in what goes into motorcycle engines?
Dick: Yes. When the EPA made changes to gasoline, first with oxygenation and now with what is called reformulated gas, there was a 3% decline in the performance level and a 3% decline in mileage. The obvious problem was that it didn't make much sense to use a cleaner burning fuel if you had to burn more of it! It defeats the purpose. They needed to make up that gap.
MXA: Can oil get that kind of power back?
Dick: Yes, at least for the truck you drive to the race track.
MXA: How did lubricants change to meet the EPA's demands?
Dick: The EPA turned to the oil companies and asked for more energy-efficient lubricants. The automotive oil guys responded by adding mileage improvers and "slippery agents." Then they reduced zinc content from approximately 3000 parts per million to 2000 parts per million. Finally, car manufacturers and the oil companies worked together to lower viscosity requirements. For example, instead of recommending 10w40 oil, they would recommend a 5w30. All of these things are counterproductive to a motorcycle. These changes have moved automotive oils out of the picture for motorcycle use.
MXA: In what ways?
Dick: Lighter oil, if not fortified in some way, doesn't have enough film strength to give high-temperature, long-term protections This is especially true in high-speed cam areas. No motorcycle manufacturer that I'm aware of would ever recommend a 5w30 oil for the average user.
MXA. What is the importance of the zinc that is now missing?
Dick: Zinc has always been an important part of motorcycle oils. It serves as a safety net. When the oil's film is ruptured, the zinc can keep metal from metal. Reducing zinc particles is counterproductive for motorcycles.
MXA: The third change you mentioned was friction modifiers. How does that hurt the motocross rider's thumper?
Dick: Slippery agents or friction modifiers can cause premature clutch slippage. Some friction modifiers will form a plate on the clutch and cause them to get slippery. These modifiers are commonly used in the new automotive oils because they are inexpensive.
THE RIGHT STUFF
MXA: Are all automotive oils off-limits for four-stoke motorcycles?
Dick: I'm talking about the standard, run-of-the-mill motor oils. They are the ones that should not be considered for motorcycles. Mobil- I or some of the synthetics may be appropriate because they have other capabilities, but they were not specifically formulated for use in single-cylinder, small-clutch, highrevving, high-load engines. You have to be extremely careful in your choice of four-stroke oils.
MXA: What makes motorcycle specific oils, like Maxima, right for four-strokes?
Dick: I can't give away our proprietary formulation, but I can tell you that we start with an additive system that was used prior to the EPA changes to oils. We use another product that is basically an anti-wear, anti-scuff additive. Our oils have the proper zinc content to offer a broader safety net.
MXA:. How about friction modifiers?
Dick: Friction modifiers increase performance by decreasing friction. They increase mileage. We use friction modifiers but are specific about our friction modifiers. We run our lubricants through a clutch test to make sure we have a friction modifier that doesn't cause plate-out. We are very selective about which friction modifiers we use.
THE RIGHT TIME
MXA: How often do you recommend changing oil in a thumper?
Dick: The YZ400 has a limited oil capacity, so it is essential to change the oil frequently. Changing oil has to be like cleaning your air filter. I can't imagine a guy practicing and riding two moto's, then going home to only wash his bike. The oil has to be changed.
MXA: Will synthetic oil extend the period between oil changes?
Dick: Synthetics will last longer, but don't try to save money in lubrication. Every time I go to a race track, I would have new oil in my engine.
MXA: The bottom line?
Dick: You get what you pay for. Stick to motorcycle oils.
