Royal Purple
Advanced
Joined: Aug 2002
Posts: 88
Likes: 0
From: TX
I know a Royal Purple dealer and he convinced me to swap my DD to to RP. I asked my GM service mgr. about using it in my Vette and he said that it could void my warranty if I experienced engine problems. My fuel mileage increased 2 mpg. in my DD. The RP dealer demonstrated to me a heat and resistance test and RP showed to be superior to Mobil l and Amsoil.
Team Owner
Joined: Jun 2001
Posts: 55,394
Likes: 1
I know a Royal Purple dealer and he convinced me to swap my DD to to RP. I asked my GM service mgr. about using it in my Vette and he said that it could void my warranty if I experienced engine problems. My fuel mileage increased 2 mpg. in my DD. The RP dealer demonstrated to me a heat and resistance test and RP showed to be superior to Mobil l and Amsoil.
Most important thing to consider is that they arent detrimental ot the car. In the past 5 years on this forum, I have observed that they are all very good. You really cant go wrong with either one of them. Its not like 1 of them will add 25k miles to the engine life.
I switched to RP for the rear fluids because I often track the car and I knowso many other roadcourse junkies who use RP with no issues. If you are going to use RP for the tranny, just make sure you dont use Auto Fluid for manual trannies.
Last edited by GR8-LIFE; Dec 25, 2006 at 09:35 AM.
Life Time NCM #2196
Joined: Sep 2004
Posts: 82,592
Likes: 1,710
From: Converse TX
I use RP in my entire Vette, becuase my mechanic uses it in his 6 Vettes he has and it seems to work fine in my 700+ rwhp setup, but if I had a stock or almost stock setup I would still use Mobil 1 without any worries
Melting Slicks
Joined: Feb 2002
Posts: 2,148
Likes: 1
From: GA
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Verdad Gallardo
Pro
Joined: Jul 2006
Posts: 529
Likes: 1
From: Princeton Texas
My way of thinking is if something comes on the market that is that much better than a competitive product it will be on the national news at 5:30 and we will all know about it. STP was one product that comes to mind. Just becouse Richard Petty pushed it (for money) later testing proved it was not the cureall it was made out to be. Latest thing being pushed by a local car talk show is "Restore". Suppose to make a new engine out of your million mile pile of junk. If someone likes RP or another product then use it. It is no dought a good product and may be an improvement, but I stay with what the owners manual says.
Burning Brakes
Joined: Mar 2004
Posts: 1,077
Likes: 0
From: Northwestern South Dakota
I still use Mobil 1 in my 2003 50th AE but a recent article in one of my corvette mags got me to thinking. They dyno tested their car with the only difference being Mobil 1 on the first pass and Royal Purple on the second pass. RWHP increased 5HP with the RP. To me that is pretty amazing for such a minor change. I haven't switched and may not. Nothing in the testing addressed warranty, longevity or any other factors but a 5HP increase simply by changing to a different oil was a surprise to me.
Safety Car
Joined: Mar 2006
Posts: 4,554
Likes: 35
From: Godfrey IL
I still use Mobil 1 in my 2003 50th AE but a recent article in one of my corvette mags got me to thinking. They dyno tested their car with the only difference being Mobil 1 on the first pass and Royal Purple on the second pass. RWHP increased 5HP with the RP. To me that is pretty amazing for such a minor change. I haven't switched and may not. Nothing in the testing addressed warranty, longevity or any other factors but a 5HP increase simply by changing to a different oil was a surprise to me.
but then +/- 5 hp is nothing and there could have been a lot of factors involved although they seemed to control the variables.
I would like to know the air temp and if gas had changed. What was the humidity difference?
These all change things. What other things were out there that we don't know about...
Race Director
Joined: Nov 1999
Posts: 12,952
Likes: 0
From: Greer SC
Cruise-In II Veteran
I use RP 10W40 on the street & RP Racing 41 at the track. ~35,000 hard miles on our C5R-427 and the engine runs great. The engine was dismantled at ~20,000 and looked perfect. I figure Mobil cut the best deal with GM, so they recommend Mobil-1. 
Race Director
Joined: Nov 1999
Posts: 12,952
Likes: 0
From: Greer SC
Cruise-In II Veteran
I still use Mobil 1 in my 2003 50th AE but a recent article in one of my corvette mags got me to thinking. They dyno tested their car with the only difference being Mobil 1 on the first pass and Royal Purple on the second pass. RWHP increased 5HP with the RP. To me that is pretty amazing for such a minor change. I haven't switched and may not. Nothing in the testing addressed warranty, longevity or any other factors but a 5HP increase simply by changing to a different oil was a surprise to me.
Le Mans Master
Joined: Dec 2001
Posts: 5,706
Likes: 552
From: St. Peters MO
C7 of Year Finalist (stock) 2019
2018 C7 of Year Finalist
Couldn't agree more. Any brand name synthetic will give you all the protection you will ever need. I use Mobil 1 simply because that was the factory fill.