How does it rate ? Thanks

 

we did a test on my 67 chevelle dyno pulls with the standard oil in the dana 60, tranny and motor our best pull was 678 horses at 3800 hp then we changed to all royal purple oils and we gained 11hp at the wheels there was also a write up in hot rod mag with the same type test using a 90s camaro and they came up with around the same numbers...now it can be said that the gain was due to ambent temps cool down times and other factors but on every run with the purple we made more power 5hp to 11hp increase 11 being the high end and granted this is a motor built for 1/4 mile trips only so how it plays out in a cummins i dont know. but i am sold on there products

 

all my boxes are purple now

 

That is the only thing I put in my trucks. The truck feels smoother. 1 to 5 I give it a 5

 

Royal Purple formulates excellent gear oils. I don't recommend their engine oils as evidenced by their very much less than stellar UOA's.

 

RP was the only one I tried that would help a problem Dana 80 in the 97 I had. The RP 15w40 gave me better UOAs in the 97 than 95% of the UOAs I see on BTOGs site. I'm really only loyal to the Maxgear - I think our diffs need some extra help especially with turned-up power. These engines thrive on any good oil routine but I still use Schaeffer semisyn to save a few$$. Craig