In motorsports, there are the topics that always seem to come up in bench racing sessions. Stuff like how your competition cheats, how you never cheat (we believe you), ideas for setup changes, money problems, and--let's not forget--the incompetence of the tech official. On the other hand, the topics that don't get as much play include volunteering to clean out the hauler, brake bleeding, and motor oil.
Besides the usual stresses that a racing engine puts on vital motor oil, dirty environment
We'll leave it up to you to decide how often you need to clean your hauler, but it's occasionally a good idea to touch on the topic of how to take advantage of the latest advancements in motor oils to free up more horsepower while keeping your engine healthy. Many racers give no more thought to it than pouring in seven or eight fresh quarts every handful of races, but considering that a film of motor oil, sometimes only a fraction of a thousandth of an inch thick, is the only thing keeping the metal components inside your engine from grinding themselves apart, it's worth making sure you are running the best stuff possible for your application.
Recently, we had the opportunity to sit down with Len Groom, AMSOIL's Technical Product Manager for Powersports, and ask him some of the questions we most often hear from racers when it comes to motor oils. Groom's specialty at AMSOIL is developing new, high-performance oils for racers on all types of machinery. He's familiar with the chemistry that goes into creating a synthetic oil capable of meeting the high demands of a race engine, and best of all, he's one of the few oil braniacs we know of that capable of explaining what really going on in real-world language. So we thought we'd pass along some of the things we learned.
Don't Mistake Cost for Quality
Back in the good old days when the cars we were racing were much more like the cars we were driving to work every day, you could pretty consistently judge the quality of a motor oil by the price tag stuck on the front of the bottle, but not anymore.
That doesn't mean that the high-priced oils on the shelf at your local auto-parts store are not good-quality oils--just that they are almost all a terrible option for your expensive race engine. The reason is because almost all of those oils are formulated specifically for standards developed to work on passenger car engines. And these days the engine in your passenger car is about as similar to your race engine as a Yorkie is to a Doberman--they both have four legs and like to growl at things, but that's about it.
Modern passenger car engines have oiling requirements based on low rpm levels (in stop-and-go traffic average rpm is barely above idle), lightweight springs, roller cams, and catalytic converters. Short trips, long oil change intervals, and low average oil temperatures mean detergents are necessary to keep sludge to a minimum and keep the oil working at a minimum functional level for as long as possible.
Does that sound like what you need for your race engine? Absolutely not. For the typical race engine you require a motor oil formulated to handle high spring pressures, flat tappet lifters, extremely high heat levels and high rpms. The oil also has to be as thin as possible to limit horsepower loss from parasitic drag in the oil pump, and it has to do it in an engine where the bearing clearances across the board are tighter than any street motor.
Synthetic oil manufacturing for racing can be quite a complicated process. AMSOIL uses the
This is why racers must search out a motor oil formulated specifically to their needs. Fortunately, there are companies like AMSOIL that specialize in exactly that. Two of the major components missing from most motor oils you will find in the automotive section of your local chain discount store are zinc and phosphorus. It's rarely listed on the label, but if you are racing an engine with flat tappet lifters, it's critical you make sure it's mixed into your motor oil in the correct concentrations.
Zinc is Not Just for Multi-Vitamins
Zinc and phosphorus are two components in a common additive package known as "ZDDP" that is critical for protecting flat tappet cams and lifters. The additives form a sacrificial barrier between the components. The pressure between the cam lobe and the face of the lifter causes it to bond to the metals, and it's the ZDDP that eventually wears away instead of the surfaces of either the lifters or cam lobes.
But the chemical components in ZDDP additive packages will clog expensive catalytic converters and also aren't good for oxygen sensors. Plus, ZDDP is no longer all that necessary in modern passenger car engines because almost all use roller lifters or followers in their valvetrains. As a result, the amount of either zinc or phosphorus in modern oil formulations for passenger cars has decreased significantly over the years, so you will need to look for an oil formulated for racing.
"To a certain extent, the more you have of it (zinc and phosphorus), the better off you will be," Groom says. "For oils formulated to run in an engine with solid flat tappet lifters, you will usually see zinc levels in the neighborhood of 13 to 15 parts per million (ppm). And that's about the same amount for phosphorus, too.
"Now, you will want to be careful, because some companies will combine the two and give you that number. That's walking a real ragged edge because you aren't certain what you are getting. We always give you those numbers for zinc and phosphorus separately so you can know exactly what you are getting. You may have to do some research to get those numbers. They may not be on the packaging, but we've got them on the AMSOIL website (www.amsoil.com). With other companies you may have to make a few calls to find out, but as long as you have 1,500 ppm of both zinc and phosphorus you should be OK."