What Engine Oil do I need to run for my 4-cycle mini bike or racing go kart?

It doesn't matter the vehicle or engine; one of the most frequently asked questions is, "What engine oil should I run?"

Generally, when asking online, the responses range from negative comments because of how often that question is asked, personal recommendations, or affiliates selling you on a particular brand. Yet, there rarely is any advice or information that gives a reason for which oil to use.

Engine oil is hard for most consumers to understand as it requires working mechanical and chemical knowledge and research. Marketing oil is complicated because putting a concise understanding on a label or ad is challenging, which leaves each brand or type of oil appearing either generic or selling snake oil(pardon the pun). 

Before we help you choose the right oil, we want to review a few frequently asked questions. We didn't expect to write a long blog, but it shows that a single blog cannot cover the depth of engine oils. However, we want to point you in the right direction, answer a few critical questions, and give recommendations.

Synthetic vs. Conventional Engine Oil?

For our applications, you'll always want a synthetic. Suppose we separate the additive package and only look at synthetic vs. conventional base oils. In that case, synthetics have many property advantages, from film strength, lower internal friction, high viscosity index, and lower viscosity grades. Synthetics break down less in higher temperatures, especially in critical spaces like the valve train. Since conventional oils are typically designed for older model engines, the additive package(higher anti-wear) may be better if you use off-the-shelf automotive oils. However, we have the option of synthetics with additives that are superior to off-the-shelf engine oils. As you read through, it will make more sense. 

Can I run regular engine oil from my auto parts store in my Clone, Predator, or Tillotson engine?

The short answer is no. Some have self-proclaimed success using off-the-shelf automotive oils, but only some are lucky. Others can have catastrophic engine failures.

I don't recommend off-the-shelf engine oils designed for late-model automobiles. Engine oils are developed to meet particular standards and certifications by API, ACEA, and many individual automotive company standards, i.e., GM Dexos. Emission regulations have led to engine development technology requiring engine oil chemistry changes. The most common is the differences in ZDDP or commonly shortened to 'zinc' that poisons the catalytic converter reducing its effectiveness and lifespan, and is limited to less than 800 parts per million in modern oils. Remember, our engines have flat tappet cams that require adequate anti-wear and ep additives. Other technologies include direct injection, turbocharging, and issues like low-speed pre-ignition. Our engines lack these technologies and are not scrutinized by the same standards since they are racing engines. These standard automotive oils do not have an additive package suitable for our engines. 

Would adding ZDDP additives to these oils resolve the need for anti-wear for our engines?

Again the short answer is no. Adding an additive is not all that simple. How much to add and how it is blended must be done correctly. Not all ZDDP or zinc is the same and may require additional chemistry to work effectively. If you think this will save you money, the cost won't be much different than buying the proper engine oil, not to mention the benefits of better-synergized chemistry. 

What about Diesel Oils? They have more ZDDP.

True, Diesel oils have approximately 1200-1500 parts per million ZDDP. 

However, diesel oils also have many detergents that compete for space with the ZDDP. Detergents don't discriminate between sludge, contaminants, and ZDDP. Diesel engine oil chemistry balances the detergency needed to clean soot from the oil and emission systems and anti-wear to protect the engine. Gas and Diesel engine are far different in their function and goals, so we can't expect the complex chemistry of engine oil to be one size fits all.

Diesel Engine Oils are usually higher in viscosity grade, which is not always recommended. Higher viscosities can create resistance causing parasitic performance loss, increased friction which increases heat and wear, and increased oil consumption, causing unwanted carbon buildup. Motorcycle oils have approximately 1,000-1,100 ppm ZDDP, which is adequate for flat tappets. I would recommend 5w-20 and 10w-30 motorcycle oil over diesel oil. Motorcycle and Diesel oil do not contain friction inhibitor additives that would assist with anti-wear and improving engine efficiency.

Racing Oils

Engine oils designed for racing are less restrictive in their chemistry to include higher amounts of ZDDP (1200+ ppm) and other additives for particular performance attributes. These engine oils are not regulated by emissions or dictated solely by engine technology. Instead, they are developed for the best performance for the given application. When in doubt, racing oil will provide the best engine protection and performance chemistry for our mini bike and kart racing engines. 

What are Karting PAG Oils

Introduced via the textile industry in the Carolinas, Kart Racers, including EC, started experimenting with Polyalkylene Glycol/PAG oil, which has an excellent viscosity index making the oil very stable, and low friction coefficient, and superb thermal conductivity; these oils proved successful in our kart racing engines especially adding different additives from EP(extreme pressure) and friction modifiers even creating "hot" oil that carried fuel accelerates and power adders like dinitrotoluene, benzene, and hydrazine. Hot oils are typically banned today, but many kart shops still blend PAG-Based karting oils.

Polyalkylene Glycol, or PAG, is a Group V synthetic oil. There is a good chance you won't find information for PAGs as an automotive engine oil. Instead, you may find them used in everything from turbine engines to industrial compressors to cutting fluids. You won't find them as automotive engine oil because they are incompatible with mineral-based hydrocarbon oils and particular seals. They are also much more expensive and less accessible.

Since they are incompatible with automotive oils, they have a mixed review in karting. Mixing oils without knowledge or experience can increase wear, reduce performance, and often causes residue or sludge to form. Usually, one is to blame and labeled as a bad oil. If you are changing oils, ensure their compatibility; if in doubt, you must flush your engine before using a new oil. Most PAGs are water soluble, which can lead to corrosion if your engine is stored with PAG oil. 

Another area for improvement with karting-specific oil is the need for more technical data to be provided. For example, many kart oil blenders don't list any viscosity grade; instead, its non-standardized light, medium and heavy oils. 

Non-PAG Karting Specfic Oils.

Synthetic karting oils are typically made of Polyalphaolefin(PAO) and ester-based oils. Since 4-cycle kart racing is a niche sport and is less prominent than 2-cycle racing on an international level, there are very few 4-cycle "kart-specific" oils made by commercial manufacturers. The most common is the Amsoil 4t engine oil for the Briggs LO206 Engine. 4T engine oils are 4-cycle motorcycle oils(2T are 2-cycle oils), which closely resemble the demands of our karting and mini bike engines, except for a wet clutch setup and gearbox. That means there will be a lot of anti-wear and ep additives but little to no friction inhibitors. Still, engine builders and racers have widely excepted these oils due to the protection they provide. Remember, the Briggs LO206 is a sealed engine, and the oil must be able to protect these engines from wear, oxidation, and corrosion since rebuilds are not an option.

We can't confirm other karting-specific oil properties since little information exists. We suspect they are either 4T or racing engine oils.

How much oil do I use?

We wanted to cover this question because it comes up occasionally, especially when there is an oil-related issue, such as excessive oil from the valve cover breather or in the catch can. For a stock rpm engine, 14-16 ounces is acceptable and recommended by most manufacturer's engine manuals. However, for rpms above 3600rpms, the splash lube system is spinning faster, and the crankcase pressure is usually higher. The oil gets pushed out with higher amounts of oil. We recommend using 13-14oz of oil in your small block engine, reducing the amount of oil pushed out the valve cover breather or in the catch can. If you run 13-14oz and still have this issue, you may have a fuel dilution problem, common with methanol engines where you gain several ounces of fluid in the crankcase. To resolve this issue may be a carburetor tuning problem, excessive idling, or a ring seal or assembly problem.

What oil do I run with methanol?

Researching and talking with oil producers about methanol-fueled engines can be tricky. That is primarily due to the differences between our small engines and racing automotive engines. 

Methanol draws in a lot of moisture. Consider a lot of open-kart racing is done in the south during the summer when it's hot and humid. The methanol you have stored in containers or your kart's fuel tank pulls in moisture before the fuel hits the carburetor. As the fuel hits the air entering the engine, its picks up the water vapor during induction. You'll often see condensation around the carburetor and intake manifold as the methanol cools the ambient air.

Since the volume of methanol is 2-3x more than the gas-tuned carburetor, fuel dilution is problematic, which means water contamination is a problem too. 

Our splash-lubricated engines have less control over oiling than a pressurized system. While every engine deals with windage in the crankcase or block, our engines don't have a pan which usually has baffles to collect and control oil within the engine. Instead, the dipper on the connecting rod, crankshaft counterweights, and even the crank and camshaft gear slings and atomizes the oil. It emulsifies the fuel and water containments with the oil resulting in 'milky' oil.

All oil producers agree that engine oil be formulated with dispersants and demulsifiers to handle race fuels, including methanol fuel dilution. It is another reason racing oils are superior to other types of engine oils when it comes to these engines. Your standard off-the-shelf automotive oils are not designed to address these concerns. The dispersants and demulsifiers are made to separate and prevent the mixing of the oil and contaminants from allowing them to evaporate or drain during oil changes. 

I have listened to debates on base oils (conventional vs. synthetic). Some have said the base oil is less crucial, and the main concern is the dispersant and demulsifiers. In contrast, others have said conventional or mineral-based oils are less miscible with methanol at lower temperatures allowing the fuel to evaporate sooner. Water containments can also cause particular esters to become acidic, leading to corrosion over extended periods. Additives for anti-oxidants and anti-rust help prevent these issues. With a splash lube system, we're not sure you'll see any benefit from using a conventional oil since the oil and containments are violently mixed together.

Also, we change the oil frequently, especially when running methanol. Our engines don't have oil filters that capture containments and deposits. Fuel dilution breaks down the viscosity and additives to reduce performance and protection but also increases fluid volume in the crankcase, which increases mechanical resistance, further reducing power. Chances are you are changing the oil after each session. Since synthetics offer more significant performance advantages, we will use synthetic oils. 

Methanol is challenging to manage, primarily due to the volume of fuel used. You can reduce fuel contamination by improving the ring seal with good ring packages, engine oil, cylinder bore honing and surface texture. 

While some carburetors idle better than others, most fuel dilution happens at idle, especially when the engine is cold. Don't start your engine until you can pull out on the track, if possible. Getting out on the track, you can load the engine to increase cylinder pressure and temperature for the rings to seal. Rings will not seal well if the engine doesn't have a load on it. Idling can wash the oil off the cylinder walls, worsening the problem. 

How often do I need to change my oil?

There isn't a one-size-fits-all when it comes to oil changes.

Running methanol engines, you are usually in a highly competitive environment where we would change the oil after almost every session. I recommend changing it every half-race day at a minimum. Usually, after practice before qualifying and then after the feature. Methanol needs to be flushed after every race day, with no exceptions.

Typical Oval or Sprint Karting running gas changes the oil at least once every race day or every race weekend, at minimum. Remember, we don't have oil filters. The oil may still have much life left in it, but it's highly contaminated. 

If you are endurance racing every 2-4 hours, it can vary depending on how radical the engine is modified, the rpm, and how well the air filter works. Change the oil for mild or recreational engines between 6-10 hours. The reason is often running engines with less rpm, less compression, ignition timing, etc. 

Usually, air cleaners are not part of the conversion when it comes to engine oils because most are concerned with the advantages of the oil itself. Use high-quality air filters to extend your oil change intervals and improve engine health. Price isn't always a reflection of quality, but typical low-quality air filters range from $10-15, whereas high-quality can be $30-60. On a clean asphalt track, it's less problematic, but if you are running on dirt or sandy areas, you'll want to protect your engine and extend its lifespan using a good air filter, pre-filter and keep it cleaned and oiled regularly. Whether it's dirt or asphalt or low or high-quality air filters, we highly recommend using Maxima Racing Oil Air Filter Cleaner and Filter Oil for all your air filters. 

Why did we choose Maxima Racing Oils?

We chose Maxima Racing Oil, beginning with the recommendation from highly respected sources and its prevalent reputation among different forms of motorsports. In our research, we looked at not only their product and successes but the company's values. There are many good oil manufacturers with good marketing and success, but Maxima Racing Oil has the "by racers for racers" attitude that we aim for ourselves. Their oils, lubricants, and cleaners are top-tier and race and championship proven. They have great support and knowledge and a diverse product line that can help us meet the goals of our customers.

Choosing the right engine oil

So far, there should be enough general information to select a good oil for your application. I want to cover more about our engine components and design that make choosing the right oil more critical. 

First, 4-cycle mini bike and kart racing engines are industrial power equipment engines ranging from pumps to log-splitters to electric generators. The engine has considerably lightweight components and is engineered to run at approximately 3600rpms in these applications for up to 2000 hours with proper maintenance. Once the rpms are increased, and the engine is modified, you exceed the engineering and tremendously compromise the lifespan. Within many small engine service manuals, the oiling information lacks proper break-in procedures and lacks oil selection specifics outside of recommended viscosity grades. 

Let's break down the components and design of the engine:

Flat Tappet – One of the most crucial considerations is the anti-wear required for flat tappets. As mentioned, today's modern engine oils are engineered for the latest engine technologies and emissions testing. The engine oil can reduce ZDDP harmful to emission control systems like catalytic converters by going to rollers tappets or camshaft followers. Since our engines don't have to meet those standards and lack emission equipment, we must prioritize anti-wear, friction inhibitors, and ep additives.

Air-Cooled – Engine oil must do more than provide lubrication between moving parts but also aid in the engine's cooling. Since air-cooled engines are less efficient than their water-cooled counterparts, engine oil becomes more critical. Lower-viscosity engine oils produce less drag and, therefore, less friction and heat. 

Thicker or higher viscosity oils may insulate high and not dissipate, as well as lower viscosity oils. Engine oils with less traction(friction between oil molecules)and more friction inhibitor additives help to reduce friction and heat. The viscosity index also becomes essential for the oil's operation viscosity to remain stable across the temperature range of the engine. 

Tighter Tolerances and Splash Lube – Unlike car engines that are pressure lube, our engines are splash lubricated. Again lower viscosity oils can provide better lubrication where it is splashed throughout the engine and reach tight areas, including the rod-bearing journal and valve train components.

Single Cylinder & Short Rod Ratio – Generally, our engines have a very short rod ratio that can cause wear on the piston skirts, especially the thrust side. Since single-cylinder engines, especially without a balance shaft, cannot fully balance, the piston can rock laterally in the engine's bore. Anti-wear and ep additives are crucial here.

Cam and Crank Gear – While it's not a gearbox, we do have the gear-to-gear contact within the engine that needs anti-wear and ep additives which is partially why 4T oils are often recommended.

Hi-Rpm Operation – A built stocker or mildly modified engine will see rpms higher than your average and most above-average street cars. A highly modified engine can turn as much as 10,000rpms. Higher engine speeds may see more parasitic losses and higher oil consumption, with thicker viscosity oils causing carbon deposits in the combustion chamber, including the spark plug, which can foul if the carbon isn't burned off. It also means you have more deposits in your oil that can increase wear. 

Engine Load Range: The load on the engine can vary based on the weight of the vehicle, the drive train(gear ratio and clutch vs. torque converter), and chassis handling can all influence the load on the engine, and with a higher load, you'll experience higher levels of heat and pressure. The oil's additive package and film strength are essential, so a full synthetic with a high viscosity index is recommended. 

Fuel Dilution: Carburetors are tuned rich for power and to aid cooling, especially when running methanol. The fuel can enter the crankcase, which isn't a good lubricant. Poor bore alignment, bore finish, ring package, and engine break-in aggravate the problem. Good racing oils will include dispersants to help, but it's best to prevent this problem as much as possible. 

No Oil Filter – Since we have no oil filter, you'll change your oil often, but we also want to reduce deposits and wear as much as possible. Collectively, the best match of viscosity grade and additives that reduce carbon from occurring and cleaning and dispensing them when they do so that they leave the engines during your oil change. 

Oil Operation Temperature – Most oil producers recommend viscosity grade based on the oil operating temperature and the component tolerances. The reason is that the oil's operating viscosity needs to be adequate for protection and reduce resistance created by thicker viscosity. Imagine a 15w-50 oil operating at a high oil temperature could have less viscosity than a 10w-30 running at a cooler temperature. Drag Racing or kart qualifying sessions would run a lower viscosity oil than one running an endurance race. 

Hopefully, you see the purpose of choosing the right oil, which includes using the right break-in oil and procedure. 

Maxima Racing Oil Break-In Oil – Good Break-in oil has little to no detergents to not conflict with the ZDDP, which creates a protective, sacrificial barrier or film on metal surfaces. Engines should have a break-in time to allow the rings to sit and for an anti-wear film to build up. To do this, run the engine with a load around peak torque for maximum cylinder pressure. It may seem contrary to what you've been told or even how your engine manual tells you to break in the engine. However, they lack many crucial details, including the proper break-in oil. 

Anti-wear, like ZDDP or zinc, requires heat to activate, and we need that to happen as soon as possible to prevent premature wear. I mentioned that not all ZDDP is the same and how quickly it can activate or burn in. The fast-activating ZDDP chemistry allows it to create a sacrificial barrier quickly while slower-activating ZDDP can build a thicker barrier at higher temperatures and pressures. 

For most stock engines, you can run them on your mini bike or go-cart just below the governor engagement. You can ride the vehicle as usual. After 10-15mins, you can change to your recommended engine oil. 

You need to control your rpms and engine load for more modified engines. Try to keep the engine around peak torque. If unsure where your peak torque is, run the engine between 3400-5400rpms. Run the engine up and down in this range for 10-15mins. Running the engine for a practice session or two works very well. 

If you have a dyno, you can watch the power increase as the rings seal better. Usually, after running the engine 3-4 full-power pulls, you'll see the ring's seat.

We recommend using Maxima Racing Oils 5w-16 Break-In Oil for all gas small block engines. The lightweight oil is ideal for these small engines with tight tolerances—or 10w-30 bigger engines like the GX390 or 460 Wildcat big blocks.

After you break in your engine, you'll want to drain and refill it with your engine oil. We have a few different recommendations that will cover all of your builds.

Kart Racing - Maxima Racing Oil RS 0w-20 checks off all the necessary oiling needs of our engine and all the performance benefits we want from an oil. The low viscosity helps tremendously to improve the engine performance in a compounding way. The lower viscosity will reduce the drag and resistance the piston rings and other components create. Drag produces friction which increases heat(lower viscosity also dissipates heat better) and wears, further reducing performance. That means that the viscosity alone makes the engine run cooler, makes more power, and reduces wear. To amplify that performance is the robust additive package of anti-wear and friction inhibitors and all the essential engine oil properties to keep the engine running strong and clean. 

Also, It has one of the highest viscosity indexes of any 0w-20 we have found on the market, which makes it a very stable oil over a wide range of temperatures and engine loads. 

We've created a chart with different racing oils with 0w-20 or the closest available viscosity grades to compare the viscosity index of each oil. While all the listed oils are good, the viscosity index is one data point that offers some insight into the quality and performance of the engine oil; the higher, the better. 

Drag Racing – These extreme builds typically do not run for more than a few seconds. It's also where power counts the most. Usually, these engines don't experience a lot of temperatures, and the oil temperature is very low. In these cases, we can run very low-viscosity engine oil. 

We recommend using Maxima Racing Oil PS0 Ultra-Low Viscosity Racing Oil. Designed explicitly for championship-winning Pro Stock engines, this oil is made for power optimization. This oil may benefit short qualifying sessions in karting before changing to a heavier weight for their feature or main race.

Recreational and Cruisers - Our concerns with these builds are usually longer oil change intervals. Since most of these engines are mass-produced and use stock bores without corrective bore and honing and stock rings, the rings don't seal very well. Over longer oil change intervals, the oil can be diluted with fuel reducing the viscosity and lubricity of the oil. We use Maxima Racing Oil 10w-30 Pro Plus oil very frequently when we are unsure of the environment or maintenance schedule of the engine. Oil changes usually range from 6-10 hours. 

4T engine oils are engineered for 4-cycle motorcycle engines, which must protect the engine components and the transmission and clutch components. These oils will have little to no friction modifiers but are engineered to endure the extreme pressures and heat created by these components under harsh conditions of racing, which experience a range of high engine loads and gear changes. 

An excellent example within karting is the Briggs/Amsoil 4T Engine Oil, which is a 10w-30 weight. Since the Briggs bottom-end is sealed, they needed an oil that would protect the engine for a long service life without the ability to rebuild or blueprint the bottom-end. 

The Maxima Pro Plus is a good alternative for all your Briggs Racing engines. For those that have used the Briggs/Amsoil 4T Engine Oil, the technical data is nearly identical, with the same viscosity index and grade. However, the Maxima Pro Plus's kinematic viscosity measures lower and may operate at a lower viscosity in your engine than the Amsoil.

Endurance Racing – What may be the most challenging oil to choose is one that is raced at long intervals. Usually, these are spec engines like the Briggs LO206 or Tillotson 212RS/225RS. 

Regardless, It's not uncommon for mini-bike enthusiasts to go on rides that can last several hours or have endurance races of their own. These engines have a strong mix of different levels of engine modifications.

We recommend the Maxima Racing Oil Extra 5w-40; For those endurance racing, highly modified builds including a lot of bigger displacement engines, the viscosity index is 221, making it remarkable compared to the list of other racing oils and robust additive package make the oil highly versatile for various temperatures and engine modifications for longer oil change intervals. Oil changes usually range from 6-12 hours.