Royal Purple04154 15W40 Oil, 1 Gallon (128 Ounces)

I have used RP, Shell Rotella T6, and Valvoline Syntech (both semi and full synthetic), Valvoline Premium Blue and conventional dealership oil in my last 2 Cummins. The RP seems to do a pretty good job. No excessive valve noise, doesn't seem to burn off, good pressure at idle and higher RPM's (based on the RAM calculated oil pressure gauge) and runs about as cool as the Shell Rotella T-6 (190-201 F. at operating temp). I probably won't buy again though. For the price I think I am going to go Amsoil HD kit which is 12 quarts plus a filter for about $200 U.S. dollars. I'm going to try Amsoil at my next oil change. However, I have no complaints about the RP.

This is the only oil I use with my Kubota tractor. I change the oil every two years which is about 120 hours.

Yep it synthetic oil

Used this oil in my 2005 Duramax, little pricy but well worth the price in my opinion

Love it

My 6-cylinder car has over 167,000 miles on it and the motor still purrs like a... well, you know. I recently added Royal Purple 15W-40 for the first time. After driving perhaps 1,500 miles with the Royal Purple, everything seems fine. The motor still purrs. Besides, how the heck can a regular consumer like me rate a motor oil unless something goes horribly wrong? If all goes well, you simply say that it's good stuff. And how does a regular consumer justify paying the price of this stuff? Perhaps in a year or so, when the Royal Purple has 12-15K miles on it, I wll give it another review. For now, I'll just say that...having it in my engine gives me a little more piece of mind. Just a little.

I have been using this oil in my vehicles since 2012. I took my truck to the shop for a tune-up, and the mechanic recommended this oil, telling me how great it was. At first, I thought he was just trying to upsell me, but I decided to give it a try. I reset my fuel mileage to monitor the effects of the new oil. Sure enough, I started getting three more miles per gallon. I was convinced and have been using it ever since.

My son and I use these in all our trucks. When he rebuilt one of his engines, there was little wear and tear above normal for 240,000 miles. There was hardly any carbon buildup at all. So we will continue to use this in our diesel vehicles And you cannot beat the price here on Amazon. They deliver right to your front door and all you have to do is go out drain your oil put in a new filter and fill it up and you’re ready to go for another 7500 to 15,000 miles depending on your preference