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."
The true test of whether a flat tappet cam will live is usually the first few minutes after it is first cranked. This is the period when the face of the lifters and the cam's lobes are able to wear together and mate in. And because of this, extra precautions must be made to make sure the top of the lobe isn't ground off in the process.
AMSOIL's 10W-30 synthetic is a popular motor oil for racers in Saturday night classes. Its
With modern valvetrains using extremely aggressive cam profiles and super strong valvesprings to keep the valves under control, it's tougher than ever to get a flat tappet cam to live through the initial break-in. That's why the dedicated break-in additives and oils you've probably seen popping up aren't just a marketing gimmick. In addition to using a lighter weight valvespring during the break-in process, these specially formulated oils can be the difference between a happy motor that provides great power race after race and one that never makes it off the dyno.
Of course, there's more to a good break-in oil than simply dumping in more ZDDP. Groom explains, "As far as break-in oils go, you have a couple of things at work there. Number one is you want to seat the rings properly so you have good ring seal and aren't blowing oil. And number two, you want to keep the camshaft, the lifters, the valve guides, rockers and all that other stuff alive while you are doing it.
"Those two requests are pretty big--you can't sacrifice one for the other--but they are also polar opposites as far as the oil is concerned. To seat the rings, you generally have to use an oil formulation that will hurt the camshaft. So after quite a bit of research, what we have come up with is to use a conventional-based oil with a monstrous additive package. With our break-in oil, I think we are up there at 2,500 ppm on both the zinc and phosphorous. In fact, you can't put any more in there or it starts to fall out! And by using a conventional versus a synthetic-based oil stock, what we have found is it seats the rings extremely quickly, and the cam and the rest of the valvetrain is properly protected while that's happening.
"One thing we try to remind customers is that a break-in oil isn't designed for racing. On the race track you will put a lot of heat into your oil, and being able to withstand that heat isn't a priority for a break-in oil because it doesn't see that much on the dyno. So we've designed our break-in oil so that once you finish your break-in and pull the engine off the dyno, its job is done and it is ready to be drained out. You are ready to put in your regular oil and go racing."
AMSOIL has the capabilities to provide oil analysis for racers right out of their own faci
Issues with Assembly Lube
Interestingly, Groom says that the humble tube of assembly lubricant is another area where AMSOIL has veered away from the usual solutions to make an advancement. Most assembly lubes used by race engine builders are one of two basic mixtures. Some manufacturers use a grease as an assembly lube. Unlike oil, grease doesn't run, so it is likely to remain where it was applied even if the engine sits for a while before it is finally cranked. The problem with grease-based assembly lubes, however, is that some resist dissolving in motor oil once the engine is run. As a result, after the engine is run all that assembly grease winds up in the bottom of the oil pan near the oil-pump pickup or lining the oil galleries. Often, that stickiness that allows it to stay where you put it means it will stay in the bottom of the oil pan or galleries through multiple oil changes and finally only gets cleaned out at the rebuild.
The second option also has its own drawbacks. Instead of using a grease base, a manufacturer can use an oil base with a tackifier to make it stickier. But Groom says a tackifier really only makes the assembly lube want to stick to itself. "I've done tests with lots of different oil-based assembly lubes that used tackifiers," he says. "I put them on bearings and then turned the bearing on its side to see what would happen. Instead of the assembly lube staying where you put it, it just slid off in one big glob.
"When we decided to produce an assembly lube," he continues, "the best solution was to take a very different approach. We stayed with an oil base for the assembly lube, but we brought the tackifier level way down and drastically increased the viscosity of the oil we were using as the base. So our assembly lube has a viscosity that is literally off the charts. So what it does is it sticks to parts and it stays there. It won't run off of the bearings, so if your engine has to sit for a while before you are able to run it, that's OK. Plus, since it is an oil-based product it very readily dissolves into motor oil. When you drain your break-in oil, all the assembly lube goes with it. It doesn't leave any of that grease sludge in the bottom of your oil pan or your oil galleries."
AMSOIL's break-in oil uses a conventional oil base-stock to help seat the rings quickly an
We mentioned earlier that race engines produce a lot of heat, and that's no surprise. But it does create a pretty significant hurdle for performance oil manufacturers. Racers want to be able to run the thinnest oil possible to reduce parasitic horsepower losses, but just because they use a 10W-30 oil (or lighter) that doesn't mean they are going to go any easier on their engine on race day. Thinner oils means tighter bearing clearances are required, so the oil that is providing the cushion between the crankshaft's main and rod journals and the bearings stay just a little bit longer and the oil temp in that area can be quite a bit higher than what you are seeing on your gauge.
The constant battle with racing oil is to make sure it can still provide adequate protection at extremely high temperatures. And when we are talking about protecting the bearings, we're talking about film strength.
"When it comes to the bearings, the one that gets worked the hardest is the bearing shell in the top side of the rod," Groom explains. "The reason is because when that cylinder first fires, that's where that force is going. (The spark plug fires the air/fuel charge before the piston reaches TDC, so combustion pressure is initially pressing down on the piston and rod while it is still travelling up in the bore.) Everything in that engine is depending on a very thin film of oil. And if the engine fires so hard that it is able to compromise the strength of that film, then pieces of metal start touching and that's the beginning of an engine failure. You want the oil to have enough strength to be able to withstand those forces so that you maintain what is known as hydrodynamic lubrication, and the crank's main and rod journals and the bearings never actually touch.
"A lot of oils, when you heat them up they thin out and the film strength goes away," he continues. "When that happens the parts get dangerously close to touching, and then the heat snowballs and goes out of control. But if you can get the oil to maintain its film strength under extreme heat, then everything tends to level out.
"A good indicator of that is when you get out of the throttle at the end of the straight going into the corner, the oil pressure gauge doesn't lay over to zero. We've worked very hard to produce a line of oils that maintains its film strength at all costs. I've seen our oils in situations where we are at 330 degrees on the cold side of the dry sump pump. That's hot, and it is still maintaining pressure, so that's really good."
Groom says AMSOIL decided to take an unusual approach with its engine assembly lubricant.
While speaking with Groom, he continually referenced what he was able to learn from performing oil analysis from different race cars. For example, he helped one race team determine exactly how long it could safely go between oil changes given the specifics of the track conditions and engine it was running. The team was able to save money by extending its oil change interval while still having confidence that its engine was properly protected. We asked Groom how regular teams could achieve the same thing even if they don't have access to high-tech analysis like the oil manufacturers. To our surprise, Groom says that AMSOIL offers its oil analysis services to anyone who wants to take advantage of it.
"That's something that we probably don't make enough people aware of," he says, "but we do offer it, and it can be very helpful to a lot of teams. Oil analysis is something that most racers under-utilize because they change their oil so often, but I can tell you through oil analysis how much fuel they are putting past the rings. I can tell you if the air filter is loose. Because as soon as you get a little sand in the engine the iron number goes up in the oil. Racers by and large hate to spend money on oil, so they are always asking ‘how long can I go before I have to change it?' And how long you can safely go--especially when you are racing on dirt--depends on a few very important factors. Number one is the air filter, number two is the fuel getting into the oil, and number three is the quality of the oil itself.
"I can tell you, for example, by doing an oil analysis if the air filter isn't sealed tightly and is letting dirt or sand into the engine. That's because the amount of iron in the oil will go up real fast. That's the grit getting past your air filter wearing your cylinder liners and your rings. And if fuel is getting past the rings, then the fuel level in the oil goes up. When that happens it reduces the viscosity of the oil, and that means your protection level is going down. "Those are just a few of the things you can learn from doing a chemical analysis of the oil that comes out of your engine. And having an oil analysis done really isn't that hard. All a racer has to do when it drains his oil is to put some of it in a clean bottle and send it to us. AMSOIL does all of its oil analysis right on site. Racers may say that they don't need to do an oil analysis because they change their oil after every race, and that's great. But why not learn what's going on with your engine during that race? And if you can save a little money by safely extending your oil change intervals, why wouldn't you want to do that?"