We sent some Royal Purple hydraulic oil to a lab where I work and compared to three other hydraulic oils commonly used in our field and RP dominated to other oils in every category.

I don't even know if it is CJ-4 rated but if it is I would like to know if anyone else uses it and what their thoughts are.

I use the 15w40. I think that's the only one the recommend for diesels. But, I love it and strongly recommend.

x2.

I also use the RP synthetic in my rear diff, and will put some in the front diff at the end of the summer.

$$$ is the only bad part!

Yeah, its expensive, but I noticed a mpg increase, and I go a lot further between oil changes.

I changed my diffs and it seems to have a lot less driveline shake, just much smoother (No actual data, just the seat of my pants).

They also make a 5w40 diesel oil too..

Try RealTruck.com

Last time I paid about $27.95 @ gallon. I am using my first Amsoil EA052 filter, which was about $17.00 (about $14.00 if you are a "preferred customer" member. SOUNDS like a VERY good filter.

I use the 15-40, atf, and diff fluids from RP!

What oil change intervals is everyone using?

Have used it for years, motor is noticeably quieter, mileage went up over
1.25 mpg. I change every 5000 to 6000 miles, about when the DIC show 50%

So at almost double the change interval of dino oil (I never run dino more than 3000 mile in any vehicle), cost is not prohibative.

I got about 10,000 miles last time, but with a Quaker State filter (Dealer - strangely did not have AC-Delco). DIC showed 5% left. I cut open the filter, and it looked OK. Oil still had good viscosity and no grit in it (that I could feel).

Based on reading up on this issue on this site, GMC info, and Bob's Oil site, I think the DIC is pretty dependable if you have not gone off road or into dusty areas and drive sensibly. There is a thread on the new Amsoil EAO52 filter claiming 15,000 to 25,000 miles between oil changes with Amsoil 15W-40.

Looks like I will get about 10,000 miles on this batch of Royal Purple according to the trend on the DIC. Those who change earlier are doing it either for peace of mind, or because they do not trust the DIC, or because that's how they learned to do things in Dino days, IMO.

I've gone 17,000 miles on RP 15/40 and the lab asked why I changed it because everything looked good. I change the filter at 5,000 miles my 01 has almost 130,000 miles and sounds and runs like the day I bought it. My next change is going to be with the 5/40 if it is diesel rated. I've used RP synthetic compressor oil for 10 years or more and have had real good luck with it.

We sent some Royal Purple hydraulic oil to a lab where I work and compared to three other hydraulic oils commonly used in our field and RP dominated to other oils in every category.

I don't even know if it is CJ-4 rated but if it is I would like to know if anyone else uses it and what their thoughts are.

Do not believe RP has API CJ-4 rating yet.

Guess I'll have to wait for the CJ-4 rating. That should make the price go down lol

How many of you running Royal Purple still have the infamous typewriter noise?

How many of you running Royal Purple still have the infamous typewriter noise?

?????????????????????

I only run RP in my wife's G35 and it made a big difference:D. I didn't even know they had Diesel products until right now!:eek: I don't think any store around here sell the RP diesel oil :mad:

Try thia thread
http://dieselplace.com/forum/showthread.php?t=162312

RP 15w40. I plan to go about 10,000 miles,then change the filter and top it off. After another 10,000 miles, I'll change all fluid.