XPR 10W/40 (formerly labeled Racing 41) is designed for marine, oval track and endurance racing. Capable of withstanding long intervals of extreme heat. Works well with alcohol and methanol. Very popular in sprint cars, late model and World of Outlaws. Viscosity is typical of a 10W40 oil.
Racing Beat has been recommending the use of synthetic oils in rotary applications for several years. Our research has found that synthetic oils provide superior friction reducing between sliding surfaces, reduced foaming, and lower oil temperatures. We have tested several different synthetic oils and have found that while most offered improved wear and lower oil temperatures, none offered any horsepower gains... except for Royal Purple!
Our in-house testing has yielded up to a 2% performance increase after changing from mineral-based oil to Royal Purple Synthetic Motor Oil. How could this be? Jim Mederer, co-founder and chief engineer at Racing Beat, was truly puzzled. With over 35 years of professional racing experience under his belt, he has seen and tried just about every "new" lubricant that hits the market. All offered better wear and lower oil temperatures but none offered any horsepower improvement. After spending time consulting with the engineers at Royal Purple to better understand the reason for the horsepower gain, it was explained that the secret was the proprietary ingredient "Synerlec". This Synerlec ingredient provides an ultra-slick film on internal engine components to significantly reduce power-robbing friction. Less friction equals more power!
Other professional engine builders have confirmed that Royal Purple Synthetic Racing Oil delivers measurable horsepower gains. Independent dyno tests show increases up to 5% (on smaller displacement engines) with nothing more than an oil change.
Rotary vehicle owners, do you have questions such as these?
"Can Royal Purple Motor Oil be used in a rotary engine?"
"Mazda makes a statement in the Owner's Manual not to use synthetic oils in a rotary engine, why do you say that it is OK?"
"I heard that synthetic oil doesn't burn like mineral based oils and will coat the inside of the engine with deposits."
Well, we have some good news! Royal Purple has added a section to their FAQ page on their corporate website that answers these important questions. To review this page, follow this link.
We also provide information regarding the use of synthetic oils in the rotary engine in the Racing Beat Tech Tip Section of the website, follow this link for more information.