Royal Purple 04154 / 300905 Duralec Super 15W40 CK-4 Motor Oil Synthetic - 1 gal. (Case of 3)

Royal Purple ,Good product! Use in my 2004.5 Dodge 3500 HD 4X4 CUMMINS 24V. I have used this oil for 19 years. My truck has 5168962 now and still pulling away. I change every 5000 miles.Was inside motor for injectors and seal,looked like new. Royal Purple lives up to its reputation and my truck is proof. Oil is slick and really sticks to parts like a synthetic oil is designed to do. Would recomend over Rotella any day.

Using this oil make my duramax engine sound better than ever. Runs smoother and quieter than if using other brands. Definitely worth the buy!

Great

I run this in my 2011 Duramax I was previously going through about 2 qts every 2,000 miles (depending gow hard I was working it) switched to royal purple and now I use NONE this Duramax has had extensive engine work bigger injectors bigger turbo different crank and connecting rods new injection pump and air dog lift pump it is deleted Fithian a 5 stage tuner and turns right at 560hp at the wheel as a daily driver and after royal purple I am also now getting low 20's for fuel mileage of interstate and get "25 ish" on regular highways at 55mph I have now started running royal purple in my tractors as well love the product!

I can't seem to find anyone that carries RP 15w40 locally. I run RP in my Harley and love it. Recently bought this truck and will be running RP in it. Big fan of the performance and cleaning of Royal Purple oils.

A few reviews rate this oil as not all it could be for the money. Yes, it is a bit pricey. But for my 2011 Itasca Meridian coach equipped with a Cummins ISC 380HP diesel, nothing compares. I have my oil tested annually and the reports are good. I am able to get about 10K miles between oil changes. I use this brand in my generator and car. Have tried others but I could tell that performance always suffered. This is a very sticky oil and does thicken slightly towards the end of its useful life.

Everyone knows royal purple’s reputation for great products. I have used their oil in my diesel engine for ultimate engine wear protection. Pricey but so is another engine. This will help your engine last longer with fewer oil changes.

Great Product! I have used RP oil in my diesel for the past 3-4 years with NO issues. Please update your post to include The CK-4 rating covers CJ-4 and CI-4 applications. Overall highly satisfied.

My favourite #1 go to brand of engine oil. Royal Purple by reputation.I'm so sick of oil changes but when I must I use Royal Purple (every 5500-6500km, filter every time as well)

Only the best goes n my diesel