View Full Version : Oil Test

Twice Bitten
08-23-2007, 11:36 PM

08-24-2007, 07:31 AM
Nice find! Where is the Amsoil in the test???? :(

08-24-2007, 07:33 AM
Wow, cool article...so which oil will you guys use? It seems Royal Purple did very well...way better than a dino oil, like I use.

Also, here are some notes from a friend of mine (Amsoil user) regarding the tests and outcomes:

"The test is one of the better tests out there although it only measures one facet of performance.
- Accuracy: the test is greatly dependant on starting with a perfectly round, smooth race which is hand polished between tests. This is critical to giving contestant #2 a fair shake. These guys probable did a good job, but Iíd want to see the field notes and pictures.

- Viscosity: not all oils tested were the same viscosity. This gives an unfair advantage to heavier oils. Iíd expect any oil with a 20-50 grade to have a better chance than a 0-40 or equivalent. Still I liked the test a lot.

- Temperature: All oils break down eventually, and the temperature varies widely. It would be important that any oil chosen would be stable at your engine oil and component temperature. Royal Purple is good, but I do not know the magic temperature.

- Volatility: all oils loose some volume as vapor under operating conditions. This varied WIDELY between oils. 20% loss for Pennzoil and 3% Amsoil. I donít know about RP(Iím sure itís good). This is usually a function of the lighter Molecular Weight molecules evaporating, leaving the heavies behind. The more uniform the MW, the better performance.

- pH stability: This is serious business. Blow by gasses are NOT stable and react with anything they come in contact with, and contain a high percentage of water vapor from combustion. Reacted oil is typically a fatty acid in nature and depending on the water content drive the pH low, causing significant corrosion during off cycles of the engine. This was the original basis for the 3 month interval. All oils have pH buffers and some oil molecules are more resistant to blow by gas oxidation than others. This is why Amsoil stands by their oil for 12 months and longer if you do a test to determine if the oil retains enough buffer agents for continued operation. RP is also a good oil on this front, although I do not know the specifics.

- Sludge suspension: blow by gasses end up creating large organic particles. Good oil can keep these in suspension, poorer oils allow the particles to drop out."

08-26-2007, 01:11 AM
Great find!

I hope this is true about RP. If so I have no worries.:thumbsup:

08-26-2007, 01:34 AM
Excellent find!!!

Royal Purple street oil here also...

Hoping to keep everything in the engine...



08-26-2007, 11:05 AM
GREAT article - Looks like RP is the best buy - I've been using Mobile 1 for years and feel betrayed. Shame on Mobile :mad:

I'm now a Royal Purple customer. :eek:

Twice Bitten
08-26-2007, 12:04 PM
oil comparison test


Here is part one. Pressure test.

1. ROYAL PURPLE Racing Oil full syn 20W50 withstands 295,722 psi

2. ROYAL PURPLE Street Oil full syn 10W40 withstands 131,432psi

3.VALVOLINE DURABLEND semi-syn 10W40 withstands 23,858psi

4. PENNZOIL semi-syn 10W40 withstands 9,200psi

5/6. Tie RED LINE full syn 5W40 withstands 6,389psi

5/6. Tie MOBIL semi-syn 10W40 withstands 6,389psi

7. SHELL semi-syn 15W50 withstands 2,920psi

8. SHELL full syn 5W40 withstands 2,567psi

9. CASTROL full syn 0W40 withstands 2,011psi

10. MOBIL 1 full syn 0W40 withstands 1,540psi

09-23-2007, 02:25 PM
Any particular oil filter to use with RP? I have seen Mobil1 users get Mobil1 filters...

09-23-2007, 04:14 PM
WOW!!! I may just end up switching to royal purple through out the whole car. What oil weight and filter do you all use? BTW I am now using Mobil 1 and will be switching to RP!!

09-23-2007, 05:55 PM
There are better then oe filters out there but I have not researched them ...

I work at a Linc.Merc dealer so I can buy oe stuff at a nice price... though Wally World does beat my 10% over cost price sometimes because of their trainload price breaks.

Therefore I use a Motorcraft FL 820 S filter.......... and RP 10W30 street oil(prefered for my usage and climate)

or 5W30(if I can't find the 10w30... or if I was in a colder climate).

I don't like the 5W20 weight... though it is slightly better for fuel economy. :doubt:

09-23-2007, 07:29 PM
I did see a test that did do Amsoil and the royal purple was still better.

Twice Bitten
10-03-2007, 07:28 AM
For the 2000 Cobra R 5.4L 32 valve engine,
XPR 5W30 or XPR 10W40.
There is no reason to run an SAE 50 in this engine - the bearing clearances are under 0.003 and by running a 50 wt oil is creating fluid drag as well as less flow than a multi-weight SAE 30 or SAE 40.

For the Manual transmission - RP Synchromax (3.3 quarts)
For the Rear Differential / Independent Rear Suspension - RP MaxGear 75W140 (1.5 quarts) No friction modifier is required - it is already in the fluid.
For the Power Steering Pump - RP MaxEZ Power steering Fluid (same as what is used in many NASCAR PS units)
For added cooling - RP Purple Ice Coolant Additive - add one bottle to a mix of antifreeze and water

5.4L Supercharged engine - RP XPR 10W40 - if you are not convinced on the lighter viscosity, then XPR 20W50.
This vehicle will never see any temperatures where an SAE 5W is needed and more VI improver is needed to make an SAE 5Wt act like a 50 Wt at operating temps than an SAE 10 or SAE 20 Wt.
See the attached viscosity curve as well as a picture of a Koeniggsegg that RP is factory fill on that has used a similar 5.4L Supercharged engine - but has been in production for the last 5 years.

For track events, the XPR 5W30 will provide the biggest performance gain and we have 700+ horsepower race engines running on the XPR 5W20 in dry sump circle track and road race conditions.

For track days, since getting every bit out of the morning is not always the primary focus, using the XPR 10W40 is a good conservative approach.

As for the GT - I've got a guy in the Dallas area that has done similar mods for the +700 and he's using the XPR 10W40.

The only reason to go up to the multiweight 50's if you're having a problem keeping oil temps below 230 - 240 F during track events and or are having a fuel dilution / contamination due to tuning.

10-05-2007, 12:59 AM
Jarid Martin and I used to work together at Texan L/M... He now works for RP.

Nice gig!!!

Good stuff Larry.. and sound advise and tech.

--> "a picture of a Koeniggsegg that RP is factory fill on" :eek: :thumbsup:


10-05-2007, 07:00 AM
I did see a test that did do Amsoil and the royal purple was still better.

I keep going back and forth on my opinion of the two. There is definitely marketing forces at play, and test variable can alter results in favor of each.



10-05-2007, 05:51 PM
Dam it Firme! Now I'm all confused :scratch:

Twice Bitten
10-05-2007, 07:19 PM
As Tested February, 2002

You don't think that they could of improved since then???? :dunno:

There wouldn't be any marketing on your part, :edmond: , would there? :dunno:

Ask Joe J about his engine when they tore it down? His part failure had nothing to do with oil.
IMHO, you are not gonna go wrong with most of these products. :thumbsup:

10-05-2007, 11:18 PM
If you are going to run extended drain intervals, then Amsoil is tough to beat... Seriously... It really is THAT GOOD!

But if you are going to change it once a year or more whether it needs it or not(like I do) Then Royal Purple just cannot be ignored. It is an outstanding protector of expensive engines, with an ever growing base of users, both grassroots and high end 30K race engine guys.
Yet it is also very reasonably priced IMHO for what you get.
Anyone with a Canton road race pan(or equal) will know value is also a big deal.(almost 9 quarts)

I had been using it in the 89 squire wagon(engine,auto trans, and diff)(7 years) and the 99 32V DOHC Navigator(engine and diff)(5 years) but with my recent spending binges they both now use Motorcraft Synth blend 5w30 to save a little brake pad money.

In the 04 Cobra it's in the engine, trans and diff. This car sees no mercy so I feel it is a very good idea to protect it the best I can... without breaking the bank too bad.
The trans appears to be a one shot deal since there has been no degradation in shift quality since the initial improvements from the RP Syncromax install 2 years ago.

The diff has no cooler and has been upgraded to a gear type, clutch-less, torque sensing Detroit TrueTrac which I would like to last a good long time... so... RP MaxGear 75W140 is what I use in it... It usually gets changed once a year because of the no cooler thing.

I wish I could get deals or a kick back or something from Jarid.... LOL.. but no dice... I buy everything from O'Reilly Auto Parts at the normal price.

I'm pretty confident that it's protected as well as it can be.. on my budget.

The extra horsepower is just a bonus... not the prime motivator.

08-05-2008, 10:15 PM
Would like to change the engine oil on the Shelby and Ford recommends on the 5.4 to use 5W-50 Motorcraft full synthetic motor oil. I see everyone talking about the weight of motor oil. If I go with RP, what weight do you think I could use and where can I get some?

Jimmy can you hook me up with some oil filters? ;)

08-05-2008, 11:05 PM
If I go with RP, what weight do you think I could use and where can I get some?
NAPA carries RP....and I've seen it at the new Wal-Mart they just built in the Woodlands...think it was only 5W30

08-05-2008, 11:42 PM
ProAm on Richmond carries Royal Purple in quite a few different weights, they will order it for you if they dont have the weight your looking for. Picked up a case last time I was there for a little less than $100.

My car holds around 8-9 quarts of oil, but I generally only change 6. You really cant get all the oil out of the oil coolers since they are in the front of the car and the engine is in the back.

08-06-2008, 09:48 AM
I'm not seeing availability of a 5w50 RP oil, only a 20w50.

I would probably stay with the Motorcraft Full Synth until availability improves with other full synth suppiers in your specified weight.

It's a lash adjuster thing, due to the port roof being raised. They had to also shorten the lash adjuster which changed it's bleed down characteristics forcing the use of the heavier oil. At least that is my understanding.

I'm sending a PM with pricing.

Twice Bitten
08-06-2008, 09:48 AM
10w-30 RP,
TV Ford probably has the best price in town.

08-06-2008, 11:32 AM
10w-30 RP,
TV Ford probably has the best price in town.

Larry are you using the 10w30 RP in the GT?
If so, are there no issues with the lash adjusters bleeding down too fast, that you know of?
Probably would never see or hear a difference, but I've heard that it will dyno lower due to less lift and duration.

I'm using the 10w40 race version RP in my Cobra and not 5W20, I was using the RP 10W30 street.

Twice Bitten
08-06-2008, 11:46 AM
Yes, that is what I am going to use the next time I change the oil. I can give up a little HP that can only be measured on an engine dyno for better overall engine lubrication. Did notice a difference when you drove it??? :D

08-06-2008, 02:15 PM
Yes, that is what I am going to use the next time I change the oil. I can give up a little HP that can only be measured on an engine dyno for better overall engine lubrication. Did notice a difference when you drove it??? :D


Let's see.... I think we had to be rolling 3rd gear about 70 before it STARTED TO HOOK!

The race version oils have slightly different viscosity availabilty, but the RP race oil is more money than the 10% over cost Motorcraft.

You guys know what I like and run but I only change it about once a year.