Royal Purple Frequently Asked Questions (FAQs)

Royal Purple’s API-licensed^* engine oils are formulated specifically to meet current American Petroleum Institute (API), International Lubricant Standardization and Approval Committee (ILSAC), and Association des Constructeurs Européens d’Automobiles (ACEA) specifications for new vehicle warranties. Over the last several years, these specifications have become increasingly stringent on certain additives, particularly those commonly used for anti-wear. As such, the new warranty restrictions aren’t the best solution for consumers that have modified their vehicles or those simply looking for the greatest performance.

HPS is formulated with these consumers in mind and includes a dramatically enhanced anti-wear package. HPS is also the choice for those seeking to maximize horsepower and torque, while reducing wear, heat and fuel consumption. HPS is the most robust engine oil Royal Purple makes for non-racing applications.

*The API website lists all API-Licensed motor oils

No. Testing has shown no short or long term adverse affects on catalysts in mechanically sound vehicles.

Absolutely. HPS 10W30 and 10W40 are both formulated for use in gas and/or diesel engines and as such are ideal for those with modified diesels or those simply looking for more performance out of their diesel.

Yes. Royal Purple lubricants are fully compatible with mineral or synthetic oils. No special procedures are necessary when switching to Royal Purple.

Yes. Royal Purple currently offers many viscosity grades of API-licensed2 motor oils. To allow for proper break-in of the engine, Royal Purple recommends waiting until the manufacturer’s first scheduled oil change or a minimum of 2,000 miles in new gasoline engines. Allow 8,000 to 10,000 miles before using Royal Purple in diesel engines.

While no special oil filter is required, we do recommend upgrading to a high quality oil filter. A high quality filter will prevent contaminants from circulating through the system and causing damage.

Royal Purple now offers extended life oil filters. See our oil filter information page for more details or visit our dealer locator to find the dealer nearest you that carries our new filters.

Royal Purple suggests adhering to manufacturer’s recommended oil change intervals for vehicles under warranty using its API-licensed SAE engine oils. With Royal Purple HPS, drain intervals may be extended to 12,000 miles (20,000 Km) or one year, whichever occurs first in street-driven, mechanically-sound vehicles. For guidelines specific to your vehicle, we recommend contacting our technical department.

Royal Purple suggests adhering to manufacturer’s recommended oil change intervals for vehicles under warranty.  Vehicles no longer under warranty using Royal Purple 15W40 diesel engine oil can extend oil change intervals up to 15,000 miles (24,140 Km) or one year, whichever occurs first in street-driven, mechanically-sound vehicles. For guidelines specific to your vehicle, we recommend contacting our technical department.

A number of retailers provide us with a listing of the products they regularly stock. You can find this information on our dealer locator page. Many of retailers will special order products that they don’t regularly stock. A number of online ‘e-tailers’ such as www.summitracing.com carry all of our consumer products.

Yes. Mileage and/or age is not a factor when used in a mechanically sound engine. In high-mileage applications, we do recommend running a minimum of two short (3,000 mile/5,000Km) intervals before extending the oil drain intervals. This will enable Royal Purple’s high solvency to remove existing deposits gradually; such deposits can restrict oil flow, if excessive, as well as reduce the oil service life significantly.

Properly formulated synthetic oils will generally not cause an engine oil leak. Synthetic oils possess a higher degree of natural solvency, which can clean and remove deposits left by previous oils. The removal of extensive oil deposits can expose marginal or damaged oil seals, which may then leak. If an engine currently has excessive oil consumption (i.e. greater than 1 quart / 1,000 miles) the recommended course of action is to solve the oil consumption problem before switching to a synthetic.

No. We strongly recommend against using any oil additives as do most automotive manufacturers. Engine oils are formulated with a fine balance of additives (anti-foam, corrosion inhibitors, anti-wear, detergent / dispersants, oxidation inhibitors), and more is not necessarily better. The use of an oil additive could upset the balance resulting in reduced performance.

Yes. Royal Purple Motor Oils are composed of a proprietary formulation of synthetic base oils and synthetic additives containing iso-paraffinic diluents.

No. The dye that’s used to color the oil dissipates shortly after being put into service. The color will turn brown at some point.

First, a substantive factor in the cost of our lubricants is the cost of the proprietary additives we use. It’s these additives that give our products their performance advantages. The additives are in no way connected to the price of crude oil. Second, crude oil is used to make gasoline and mineral based lubricants. Our lubricants are formulated using synthetic base stock that is not a component of gasoline.

You may want to call other retailers in your area that are more customer friendly and who want to earn your business. If you are willing to order products online, a number of ‘e-tailers’ such as www.summitracing.com sell our products in quart quantities.

Please contact our technical department with the make, model and year of your vehicle.

Yes. All Royal Purple engine oils contain the zinc/phosphorus compound zinc dialkyl dithiophosphate (ZDDP). Royal Purple HPS and XPR lines of engine oils are formulated with a higher concentration of these elements and are suitable for both roller and flat tappet valve trains.

Yes. For stock or mildly modified flat tappet valve trains (>.525” lift), we recommend our HPS or XPR engine oils. For a viscosity recommendation, contact our tech department at 888-382-6300.

Yes. All Royal Purple Premium Oil Filters are compatible with both types of motor oils.

Royal Purple Filters meet or exceed original equipment manufacturers’ requirements. All new car warranties remain in effect when using Royal Purple Filters.

Royal Purple Premium Filters use 100% synthetic micro-glass media for superior particle removal with 99% filtration efficiency at 25 microns.

99% efficiency at 25 or greater micron based on ISO 4548-12 multi-pass test methods.

Features and Benefits:

• 100% synthetic micro-glass media for superior particle removal with 99% filtration efficiency.
• A high performance silicone anti-drain back valve that prevents dry starts, even in extreme conditions.
• An extra-heavy duty rubber base gasket that ensures a leak-free seal.
• Ultra-strength filter housing endures higher burst strength than conventional filters.

100% wire-backed synthetic media provides superior filtration while keeping low flow restrictions.

Yes, the silicone anti-drain back valve prevents dry starts by eliminating oil drain-back during shutdown. Silicone outperforms and outlasts standard rubber in both extreme cold and hot oil temperatures.

Average beta rating based on ISO 4548-12 multi-pass test methods:

• B100 = 25 (which means at 25 or greater micron; media is 99% efficient.)
• B75 = 20 (which means at 20 or greater micron; media is 98.7% efficient. Also considered absolute rating.)
• B5 = 10 (which means at 10 micron or greater; media is 80% efficient.)

Call the Filter Hotline at 1-800-882-0890. Hours of operation: M-F (7a-7p CST); Sat (7a-5p CST).

Vehicles under warranty should follow the vehicle manufacturer’s recommended change intervals. Vehicles no longer under warranty and in good condition may extend filter changes to 12,000 miles (20,000 Km) if they are driven under normal operating conditions and are using Royal Purple motor oil or other major brand of synthetic motor oil. Vehicles using a diesel oil filter no longer under warranty and in good condition may extend filter changes to 15,000 miles (24,140 Km) if they are driven under normal operating conditions and are using Royal Purple motor oil or other major brand of synthetic motor oil.  Vehicles driven in severe conditions should follow the change intervals recommended in their owner’s manual; severe conditions are defined as racing or commercial applications, frequent towing or hauling, extremely dusty or dirty conditions, or excessive idling.

When looking at a SAE engine oil viscosity grade, the last number is most important. HPM oils are intended for 4-stroke, gasoline marine engines.

If the factory recommends 5W-30, 10W-30, or SAE 30, Royal Purple HPM 30 is the best choice.

If the factory recommends 5W-40, 10W-40, 15W-40, 20W-40 or 25W-40, Royal Purple HPM 40 is the best choice.

When looking at a SAE gear oil viscosity grade, the last number is most important. If the factory recommends 75W-90, 80W-90, or SAE 90 (straight 90 weight) gear oil, Royal Purple HPM 80W-90 will work great in your lower unit/outdrive.

For 2-stroke engines, we recommend Royal Purple HP 2-C 2 cycle oil. It works great in pre-mix or oil injected applications. For pre-mix, we recommend using the manufacturer recommended mix ratio.

Yes. While the Royal Purple SAE and Racing engine oils may be used in motorcycle applications its Max-Cycle line of engine oils have been formulated specifically for motorcycle engines and transmissions.

No. Royal Purple provides exceptional film strength for excellent metal-to-metal protection, yet it is also safe for use in wet-clutch applications.

Follow the manufacturer’s recommendations regarding viscosity. Most manufacturers recommend a 10W40 for 4-cycle, liquid-cooled motorcycles. Air / oil cooled motorcycles typically specify a 20W50. Check your owner’s manual for verification or contact Royal Purple’s Automotive Technical Department at 888-382-6300 for assistance.

Royal Purple suggests adhering to manufacturer’s recommended oil change intervals for vehicles under warranty. Vehicles that are no longer under warranty can frequently double or triple the number of miles between oil changes depending on the vehicle, its condition, the way it’s used (excessive idling), and the oil filter that is used. For guidelines specific to your vehicle, we recommend contacting our technical department at rpautotech@royalpurple.com

For Evolution and Twin Cam motors, Royal Purple’s Max-Cycle 20W50 is recommended. For Sportsters and Buell motorcycles, Royal Purple’s Max-Cycle 10W40 may be used. Check your owner’s manual for verification or contact Royal Purple’s Automotive Technical Department at 888-382-6300.

Royal Purple Max-Cycle 10W30, 10W40 or 20W50 motor oil may be used in the primary tank. For transmissions, Royal Purple recommends Max-Cycle 20W50 or Max-Gear 75W90. NOTE: DO NOT use Max-Gear lubricants in the primary.

For motorcycle 2-cycle gearboxes and 4-cycle gearboxes with a separate reservoir, Synchromax manual transmission fluid is recommended.

Yes. Royal Purple uses a different additive chemistry than most manufacturers, which is the very foundation of the benefits RP offers. This technology has a distinctive odor, different from the common odor of exhaust gases to which most have become immune.

Yes. Royal Purple’s XPR racing oils are fully formulated engine oils with complete additive packages needed for long-term use. XPR’s ultra-light viscosities, XPR 3.1 and XPR 0W-10, are typically only suitable for dedicated competition engines that are built to use low viscosity engine oils. Non-ultra light viscosities, XPR 5W-20, XPR 5W-30, XPR 10W-40 and XPR 20W-50, may be used in street driven and daily driver applications, street and track duty vehicles, and dedicated competition applications with gasoline or exotic fuels. Please note: Royal Purple’s XPR racing oils do not conform to API and/or ILSAC licensing requirements and should not be used when manufacturers’ warranties are an issue.

Royal Purple’s motor oils are formulated to provide unparalleled performance and protection and comply with API / ILSAC specifications. Its racing oils vary in viscosity and formulation as compared to the SAE motor oils to provide the greatest performance gains possible without regard to API, SAE and / or ILSAC specifications.

Royal Purple’s involvement in motorsports is primarily for research and development purposes. Racing aids us in developing new and inspiring products. We are highly selective with whom we decide to work with and limit our involvement to a few select racers/teams. Inquiries about Royal Purple’s racing program should be sent to RFisher@royalpurple.com.

Royal Purple has several options for racers. RP HPS engine oils are formulated to outperform many of the “racing” oils on the market, but Royal Purple’s XPR racing oils redefine the category. Royal Purple XPR offers an even greater performance increase than its SAE engine oils. With that said, the following are some guidelines to determine which products to use. As a point of reference, Royal Purple recommends using a racing oil that is closest in viscosity to the oil the race car is currently using (e.g. a racer using a conventional or synthetic 20W50 racing oil would be safe using either Royal Purple’s HPS 20W50 motor oil or upgrading to Royal Purple’s XPR 20W50). The tolerances to which the motor was built can play a role in an oil recommendation. Looser specs (e.g. greater than .003″) might require heavier weight oil than a motor built to tighter specs (e.g. .002″) to maintain idle oil pressure. Keep in mind that it is much easier to be conservative and use heavier weight viscosity oils and then go lighter when experience and comfort level dictate.

Yes. Royal Purple’s lubricants can be used with exotic fuels. For the best protection, Royal Purple has formulated its XPR specifically with this in mind. The XPR oils are formulated to combat fuel emulsification to hold up even better than Royal Purple’s other engine oils in alcohol and methanol applications. Royal Purple’s other synthetic engine oils will still perform better than conventional racing oils; however, significant fuel dilution will reduce the effectiveness of these oils much more than the XPR oils.

We recommended using Royal Purple Break-In Oil, formulated to allow optimal ring seal and protect rotating assembly components. As a general rule, follow your engine builder’s guidelines. On street setups, the rings should seat within the first three or four times the engine is brought to temperature. After the rings have seated, change to Royal Purple.

Yes. You may use Royal Purple HPS or XPR engine oils on newly coated bearings without needing a mineral oil break-in period.

This can vary depending upon application and the level (amount) of contamination (i.e. dirt, fuel, water, etc.). A good rule of thumb is to find out the racer’s current type of oil and oil change interval. If the racer is using petroleum oil, you should feel comfortable doubling or tripling their change interval. If the racer is running another synthetic, you can feel comfortable doubling their change interval.

In most instances, vehicles with properly functioning cooling systems can reduce oil temperatures by 5-20°F by using Royal Purple.

Retailers choose the products they elect to stock and order for a myriad of reasons. Consumer-centric retailers will order any of the products we offer. A number of online ‘e-tailers’ such as www.summitracing.com carry all of our consumer products.

Royal Purple’s full line of “Nitro” oils have been specially formulated for use in high power nitro and blown alcohol applications.

For the 5 speed transmission, Royal Purple’s Racing ATF or XPR 0W10 motor oil is recommended. For a 3 speed, Max ATF is the best bet.

The noncorrosive, extreme pressure additives in gear oils do give off a distinctive odor, which can be magnified under extreme racing conditions. This is normal for API-GL5 hypoid gear oils containing sulfur / phosphorus extreme pressure additives.

No. Royal Purple has not found any evidence that it shows deterioration in performance after being subjected to race conditions. It is possible that fuel dilution contamination may start to hinder the performance of the engine oil; however, dyno results do not support this claim.

Either Royal Purple’s HP 2-C or XPR 2-Cycle may be used in pre-mix applications.

Royal Purple HP 2-C is recommended for stock oil-injection applications. Royal Purple XPR 2-Cycle is recommended for use with modified oil-injection metering.

For low temperature, oil-injected applications, Royal Purple’s Snow 2-C is recommended.

No. Royal Purple’s 2-cycle oils are formulated for use in gasoline applications only.

Yes. A rotary engine is a modified four-cycle engine that recommends the use of an API-licensed motor oil for street applications.

In a rotary engine, the oil lubricates the eccentric shaft bearings, thrust needle bearings and rotor bearings (similar to a crank and rod bearing of a piston engine). It also is injected into the combustion chambers to lubricate the apex seals, corner seals, and side seals, all of which helps to create the sealing mechanism (the equivalent job of the piston rings).

Royal Purple provides outstanding protection for the e-shaft, rotor bearings and thrust bearings and is suitable for the oil injection system as it has proven to run cleaner than other oils and is an excellent choice for rotary apex seals, corner seals and side seals.

Royal Purple has performed seal compatibility testing on the components used in a rotary with excellent results — including older rotary engine seals dating back to the Cosmo. Royal Purple’s Technical Services Manager David Canitz (who has been an owner and racer of rotary engine cars using synthetic motor oils since 1985 with excellent results) has been trying to find an answer to this Mazda statement for the last 18 years.

In the early development of synthetic oils decades ago, there were purportedly some seal compatibility issues. Today’s synthetic oils do not have the compatibility issues of the old oils. There is no substantiated evidence of seal compatibility issues with Royal Purple.

Here are some facts:

• The Mazda Factory racing departments recommend and use ‘synthetic’ oils including the winning 1991 Leman’s 20-G 4 rotor Mazda 787B.
• MazdaComp USA printed manual (now Mazdaspeed) recommends the use of synthetic oils for racing conditions.
• Royal Purple Motor Oils have been used in rotary engines (both race and street) for 10+ years with excellent results.
• Royal Purple Motor Oil is compatible with the bearing material, sealing elastomers and combustion seals used in a rotary engine.

If this was a problem with synthetic motor oils in general, then all internal combustion engines using a ‘synthetic’ would experience increased deposits on internal surfaces. The opposite is actually the norm.

Conventional four-cycle motor oils will typically leave deposits of carbon and ash when injected into the rotary apex seal, corner seal and side seal areas. Royal Purple’s motor oil burns cleaner due to its synthetic base stock being free of contamination and the fact that many of its additives are ‘ashless’. This may not be true for all synthetics but Royal Purple has been proven to work extremely well in rotary engines.

Royal Purple’s formulation of synthetic hydrocarbon motor oil burns at the nominal combustion temperatures experienced in both street and racing applications, whether normally aspirated, turbocharged or supercharged. (500 – 1700%°F idle to race rpms typical combustion temps)

No. Royal Purple’s motor oil is fully compatible with the elastomers found in rotary engines as well as more conventional piston engines. The oil seals, housing seals and other elastomers used in rotary engines typically consist of Buna N, Nitriles, Neoprene or Viton materials, which are also commonly found in piston engine cars.

No. If an engine’s sealing surfaces are in good condition, synthetic oil should not cause any leakage. However, if an engine has marginal seals, there is a 50/50 chance the seals will leak. A synthetic motor oil is going to have similar viscosity to that of a conventional motor oil – except at extreme temperatures. Due to a flatter viscosity curve, at low temperatures it will not thicken as much (easier winter cranking) and will not thin out as quickly at higher operating temperatures (better oil film at higher rpm).

Royal Purple recommends that the maximum oil drain / filter change interval listed in the Owner’s Manual be followed while under warranty (new RX8). For FA, FB, FC, FC Turbos and FD rotaries, extending drain intervals from two- to five-fold is possible if desired. Since the rotary engine injects oil through the use of a metered oil pump, either adding oil into the carb base plate air / fuel mixture or directly injecting oil into the rotor housing, rotary engines will consume oil of one quart per 1000 – 3000 miles. It is important to maintain the proper crankcase oil level in your rotary engine if you decide to extend oil drain intervals.

In an ideal world, the rotary engine metered oil pump should inject an ashless oil designed to burn in the combustion chamber and use a four-cycle oil in the crankcase for the eccentric shaft, rotor bearings and thrust bearings. For the street, Mazda simplified the OE system to use just one oil, that being a typical four-cycle oil for both the e-shaft as well as the combustion chamber. Royal Purple recommends using our standard HP 2-C if the metered oil pump is still enabled. The two-cycle oil being added to the fuel tank is in addition to what Mazda designed to inject and acts as a supplement or insurance. Depending upon which engine, the level of modifications (street port, Bridgeport, peripheral port, nitrous turbocharged) and application, the typical mix ratio could vary from 200:1 to 800:1.

For a pure racing application where the metered oil pump has been disabled or removed, again based on the actual engine and modification level, the ratio could vary from 150:1 to 600:1. For this application, we recommend our XPR 2-Cycle XPR 2-C or the standard HP 2-C.

A stock FD twin turbo 13B with the MOP oil injection system can typically use about one quart per 1500 miles under hard street driving. If this vehicle is getting 15 mpg, the gasoline to oil ratio is 400:1. If the oil consumption on this vehicle reduces to 1 quart per 2500 miles and fuel efficiency increases to 20 mpg, the gasoline to oil ratio increases to 600:1. The stock metering oil pump is a great system as it varies with throttle position (load on the engine). Pre-mixing has to be calculated for the ‘worst case’ that will be seen by the engine for that fuel load. Under racing conditions, that’s wide open throttle at racing rpms. This means that at idle, the ratio may be slightly fat (rich).

See our transmission lubricant cross reference chart for specific applications.

Always follow manufacturer’s recommendations or contact Royal Purple’s Automotive Technical Support Dept. at 888-382-6300 for more information.

Max ATF is an excellent, function replacement to these fluids; however, it is not a warranty-approved fluid. Consumers still under their factory warranty should remain with OE fluids, while those that have exceeded factory warranty may use Max ATF as a performance upgrade.

No, Max ATF is not recommended for use in CVTs.

For manual transmissions and / or transfer cases specifying a Ford Mercon® or GM Dexron® ATF, Royal Purple recommends either its Max ATF or for greater performance, its Synchromax.

No. All viscosities of Max-Gear are formulated with hypoid friction modifiers necessary for use in clutch or cone differentials. No additional additives are necessary.

Yes. Max-Gear possesses both API GL-5 and GL-4 certification. Max-Gear is formulated with Royal Purple’s proprietary, Synerlec additive technology to provide the exceptional film strength necessary for GL-5 applications, yet it is noncorrosive to soft metals found in manual transmissions that specify a GL-4 rated lubricant.
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Purple Ice should not be used with other heat-transfer or cooling enhancing products or “water wetters”. If such a product has been used in the cooling system, the system should be drained and flushed before using Purple Ice.

Purple Ice is compatible with cooling system additives intended to stop or slow leaks. Please note that such stop-leak products often typically put a coating on the interior surfaces of the cooling system, so the effects of Purple Ice may be diminished.

Purple Ice is compatible with all current OEM/factory and major brand automotive anti-freeze. This includes traditional green ethylene glycols, as well as OAT/HOAT antifreezes (e.g. DexCool; Ford and Chrysler orange, gold, pink; European and Japanese OEM red, pink, etc.).

Purple Ice may be added to any antifreeze / water mix; however, testing has shown higher water concentrations yield greater cooling benefits. While Purple Ice does contain corrosion inhibitors as well as lubricants to compensate for a lower antifreeze / water concentration, Royal Purple recommends a minimum of 20 percent antifreeze concentration be used in street driven vehicles because Purple Ice has no effect on the boiling and / or freezing point of water.

When using Purple Ice with an antifreeze / water mix, Royal Purple recommends adding 1 ounce of Purple Ice per quart of cooling system capacity. For straight water (racing) applications, Royal Purple recommends adding 2 ounces of Purple Ice per quart of cooling system capacity.

When used with antifreeze, Purple Ice should be added once a year or every 30,000 miles, whichever comes first, in order to maintain proper performance. When using Purple Ice in a cooling system running straight water, Purple Ice should be added once a year or every 15,000 miles, whichever comes first.

No. A higher concentration of Purple Ice than recommended won’t offer any additional cooling benefit nor will it have any adverse effects on the engine or cooling system.

Yes. Purple Ice may be used in diesel engines for improved heat transfer as well as reduced cavitation.