# Royal Purple or Amsoil Full Synthetic?



## ChiefyGTO (Aug 7, 2006)

Which do you think is better:
Royal Purple synthetic or Amsoil synthetic? Why?


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## pickinfights (Oct 3, 2006)

I put Mobile clean 5000 in mine.
I dont see that synthetic is worth the extra $.


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## Route 66 (May 30, 2005)

:agree I dont buy all the synthetic 'hype.' Been using dino oil for ever.
But if I were to have to choose, I'd go Amsoil. Only because the fact I know those who use it that swear by it. No matter what is said, they are all basically the same....just as all dino oil is the same. Its all in how you maintain your vehicle.


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## GoatMann (Jul 20, 2006)

Route 66 said:


> :agree I dont buy all the synthetic 'hype.' Been using dino oil for ever.
> But if I were to have to choose, I'd go Amsoil. Only because the fact I know those who use it that swear by it. No matter what is said, they are all basically the same....just as all dino oil is the same. Its all in how you maintain your vehicle.


Gents: 

If you do some research on the GM Forums there is an LS2 section that states the recomended synthetic for the LS2, it's been two months since I've gotten my oil changed, but I know Good Year where I get mine done carries performance Synthetic.


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## Subdriver (Dec 28, 2004)

ChiefyGTO said:


> Which do you think is better:
> Royal Purple synthetic or Amsoil synthetic? Why?


Just rejoined the world of the connected after several months underway; sorry I'm catching this one late.

When I lost an LS6 motor in my first season of SCCA racing (while running Mobil 1 15w50), I did several months of research on oils trying to determine if there was a better oil that might have helped prevent my engine failure. I primarly was looking at Royal Purple and Redline. 

What I discovered, contrary to Route 66's statement above, is that oils, both dino and synthetic, are vastly different, in both their basestock and their additives. These differences contribute to differences in performance. 

The API classifies oils into five different groups. 

Group I base oils are the least refined of all of the groups. They are usually a mix of different hydrocarbon chains with little or no uniformity. While some automotive oils use these stocks, they are generally used in less demanding applications.

Group II base oils are common in mineral based motor oils. They have fair to good performance in the areas of volatility, oxidation stability, wear prevention and flash/fire points. They have only fair performance in areas such as pour point and cold crank viscosity. Group II base stocks are what the majority of engine oils are made from. 3000 mile oil changes are the norm.

Group III base oils are subjected to the highest level of refining of all the mineral oil stocks. Although not chemically engineered, they offer improved performance in a wide range of areas as well as good molecular uniformity and stability. By definition they are considered a synthesized material and can be used in the production of synthetic and semi-synthetic lubricants. Group III is used in the vast majority of full synthetics or synthetic blends. They are superior to group I and II oils but still have limitations. Some formulations are designed for extended oil changes. AMSOIL XL Motor Oils, Castrol Syntec and many others fall into this category. 

Group IV are polyalphaolefins (PAO) which are a chemically engineered synthesized basestocks. PAOs offer excellent stability, molecular uniformity and performance over a wide range of lubricating properties. AMSOIL SAE Synthetic Motor Oils and Mobil 1 primarily use group IV basestocks. PAO is a much more expensive basestock than the highly refined petroleum oil basestock of Group III.

Group V base oils are also chemically engineered stocks that do not fall into any of the categories previously mentioned. Typical examples of group V stocks are Esters, polyglycols and silicone. Redline uses an ester basestock.

In the 90s, Mobil filed suit against Castrol for falsely advertising Syntec oil as synthetic, when in fact it contained a Group III, highly hydroprocessed mineral (Dino) oil, instead of a chemically synthesized (group IV or V) basestock. Due to the amount that the mineral oil had been chemically changed, the judge decided in Castrol's favor. As a result, any oil containing this highly hydroprocessed mineral (Dino) oil (currently called Group III basestock by the American Petroleum Institute) can be marketed as a synthetic oil. Since the original synthetic basestock (polyalphaolefin or PAO) is much more expensive than the Group III basestock, most of the oil blenders switched to the Group III basestock, which significantly increased their profit margins.

When I was trying to decide between Royal Purple and Redline, I discovered AMSOIL. What impressed me about AMSOIL was that it used the same basestock as the stock Mobil 1 (Group IV PAO basestock), but used oil analysis reports showed AMSOIL used higher levels of detergents and anti-wear additives. This was somewhat confirmed when Mobil 1 came out with their Extended Performance Mobil 1. When Mobil 1 came out with this new product, at the time they claimed that it had about 50% more detergent and anti-wear additives than the regular Mobil 1. 

What turned me off to Royal Purple were several poor used oil analysis reports I reviewed, and the fact that they did not say on their website what type of basestock they used. Other companies such as Redline, Mobil 1, and AMSOIL were very up front with their basestock, so I wondered what Royal Purple was trying to hide.

My research indicated to me that Redline was (and still is) a very good oil, but I was somewhat concerned that its basestock was Group V, an ester basestock, and I'd read a few bad reports on the ester's effects on seals in the Corvette transmission. 

As I'm now an AMSOIL dealer, I obviously chose to go with AMSOIL. Since I switched to AMSOIL in 2004, I have had no transmission or differential failures in my Z06, nor have I had any oil related engine failures (I did lose an engine due to a failed timing chain and another when the harmonic balancer came off).

Since then AMSOIL has included Royal Purple in a few oil comparisions.
There is a four-ball wear test on this page of my dealer website:
AMSOIL Series 2000 20w50

And Royal Purple was included in this extensive motorcycle oil comparison:
AMSOIL Motorcycle Oil “White Paper” (1 MB pdf file)
:cheers


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## Guest (May 12, 2007)

*oil*

I have known a few people who had major engine problems with Castrol and Valvoline ,, these oils can foam up.. 
I use Royal Purple 5W30,, what ever type you use , do not go higher then 10W40,, the 10 weight and 20 weight oils flow through the engine slower then a 5 weight and also return to the oil pan much slower, some cars have suffered from oil starvation because of this, the oil flows too slowly and Major componets will suffer, the 5 weight is a faster flowing oil..


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## Guest (May 12, 2007)

*oil*



Subdriver said:


> Just rejoined the world of the connected after several months underway; sorry I'm catching this one late.
> 
> When I lost an LS6 motor in my first season of SCCA racing (while running Mobil 1 15w50), I did several months of research on oils trying to determine if there was a better oil that might have helped prevent my engine failure. I primarly was looking at Royal Purple and Redline.
> 
> ...


I have heard good things about AMSOIL, but I can't find it around here


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## Subdriver (Dec 28, 2004)

dizzy1 said:


> I have heard good things about AMSOIL, but I can't find it around here


AMSOIL isn't carried in many stores, but is easily ordered online (which is how I get all of my products). For those that use AMSOIL regularly, this program allows you to buy directly from AMSOIL at dealer cost (same cost I pay), about 20-25% under retail:
AMSOIL Preferred Customer Program


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## UdnUdnGTO (Jan 30, 2006)

arty: Been an Amzoil user for over 30 years. Awesome product!


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## Guest (May 31, 2007)

*oil*

I use Royal Purple,,

REMEMBER GM Reccomends MOBILE ONE but they DO not REQUIRE you to use it,,.

a Major problem with ALL synthetic oils is that you should only use it in a FULLY broken in MOTOR,, using this oil on a new engine [ ANY KIND } will never allow the engine to break in properly..I used regualr DINO oil from day of delivery till I had over 8,000.00 mile on my car before I switched to synthetic,,this is probably the reason for my Stock HP readings when I had my 1st Dyno tune,, my base line was 342 RWHP


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## Good 2 go (Sep 7, 2005)

Since getting my engine work done with forged internals, my builder told me to use 20w50 synthetic. In stores around here, I've only been able to find that weight in Lucas oils.


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## Subdriver (Dec 28, 2004)

Good 2 go said:


> Since getting my engine work done with forged internals, my builder told me to use 20w50 synthetic. In stores around here, I've only been able to find that weight in Lucas oils.


AMSOIL makes a couple 20w50s. I used the Series 2000 20w50 in my 02 Z06 for a few seasons while racing in the hot summer in Memphis.

AMSOIL Series 2000 20w50
AMSOIL SAE Synthetic High Performance 20w50

If you are going to buy a case or more of either of these, you'd save money by signing up for the AMSOIL Preferred Customer Program.
:cheers


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## fiddler_red (May 9, 2007)

dizzy1 said:


> I use Royal Purple,,
> 
> REMEMBER GM Reccomends MOBILE ONE but they DO not REQUIRE you to use it,,.
> 
> a Major problem with ALL synthetic oils is that you should only use it in a FULLY broken in MOTOR,, using this oil on a new engine [ ANY KIND } will never allow the engine to break in properly..I used regualr DINO oil from day of delivery till I had over 8,000.00 mile on my car before I switched to synthetic,,this is probably the reason for my Stock HP readings when I had my 1st Dyno tune,, my base line was 342 RWHP


Hey Mr. D! So you believe in using synthetic only after break in. Actually I've heard it from many sources. I just got a GTO and it has just 1000 miles on it. This car has the Mobil 1 synthetic oil all LS2's ship with. Do you recommend draining it and filling with a regular oil and then going through the break in process again before switching back to synthetic? Please advise me, you seem extremely well versed in all of this and I'm new to it all. Thanks


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## Chrisco (Mar 19, 2007)

Just ordered some amsoil. I have RP in my engine now so I'll see if there are any differences.


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## auGTO (Jun 8, 2007)

Subdriver said:


> What turned me off to Royal Purple were several poor used oil analysis reports I reviewed, and the fact that they did not say on their website what type of basestock they used. Other companies such as Redline, Mobil 1, and AMSOIL were very up front with their basestock, so I wondered what Royal Purple was trying to hide.
> 
> Since then AMSOIL has included Royal Purple in a few oil comparisons.
> There is a four-ball wear test on this page of my dealer website:
> ...


Lets start with how you say Amsoil is up front- If they were so up front with everything, then why do they claim they meet and exceed API service, and the best protection. The new API service SM has reduced the ZDDP levels up to 40%, which is the back bone of the anti-wear protection, and Amsoil claims to meet this service. So how can they give you the best protection when Redline and Royal Purple do not have API SM oils? The math alone tells you that they at least have 40% more protection than Amsoil, or Amsoil is lieing that they meet this spec and you could lose your warranty anyways.

Then you state Amsoil has test vs. Royal Purple and Redline, but on the corp. website there is no test comparing them. You are looking at the dealers and the corp. was forced to remove it because they were looking at a lawsuit if they kept false information on their website. They do not go after the dealers, because 99% of them are just normal people who are not worth the time and money to go after each and everyone of them. This is common practice in a pyramid scheme.

The most false test Amsoil has put out is the 4-ball wear test. This test is not for comparisons of different oils from different oil companies, but the same batch to ensure the viscosity is the same and the additives are even distributed through out. Amsoil has taken this test and made it a big selling point, but even they do not know how to run a proper test. It is like the show “Are You Smarter Than a 5th Grader?” Amsoil would fail science. In a test you compare the same, but Amsoil does not. For Example Amsoil uses their racing oil 20w50, but uses Mobil 1’s European oil 0w40 and never even states what they chose from Royal Purple. for all you know it could be a 5w30 or 5w20. How is this a true test when they use a test that is made to test same batch in the same company and they do not even use the same viscosity for all the oils tested?

Amsoil makes a great product, but they are not up front nor are they honest.


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## auGTO (Jun 8, 2007)

Good 2 go said:


> Since getting my engine work done with forged internals, my builder told me to use 20w50 synthetic. In stores around here, I've only been able to find that weight in Lucas oils.


Unless you have changed the clearances of your motor, there is no need to run a higher viscosity, unless you like running hot, and consuming more fuel. This is not good for your motor or your horse power, because you are causing more friction than you need to with the thicker oil and it robs you of some of the horse power you just received by building a stroker. It is like pushing a grapefruit through a hole the size of a orange. You are going to have to work harder to push it through that hole than you need to.


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## Subdriver (Dec 28, 2004)

auGTO, 
Clearly and AMSOIL fan, eh? :lol: 
You bring up some good points that bare clarification.




auGTO said:


> Lets start with how you say Amsoil is up front- If they were so up front with everything, then why do they claim they meet and exceed API service, and the best protection. The new API service SM has reduced the ZDDP levels up to 40%, which is the back bone of the anti-wear protection, and Amsoil claims to meet this service. So how can they give you the best protection when Redline and Royal Purple do not have API SM oils? The math alone tells you that they at least have 40% more protection than Amsoil, or Amsoil is lieing that they meet this spec and you could lose your warranty anyways.


Several points in this paragraph. The new API/ILSAC GF-4 standards do limit ZDDP anti-wear additives to a level of 0.08%, or 800 ppm and all of AMSOILs street oils are labeled to meet this standard, though not all are API Starburst Certified. AMSOIL has compensated for the loss of ZDDP additives by increasing the amount of other anti-wear additives. Their oils still perform well. Here is a real world used oil analysis from one of my Corvette Customers showing the results of 5,000 miles of use on the new API SM AMSOIL SAE Synthetic 10w30 that included a full track day:
Corvette C5 Used Oil Analysis Report – AMSOIL SAE Synthetic 10w30

This analysis shows that this engine's wear metals are as low or lower than the fleet average for that lab and that engine (the Blackstone Fleet average for the LSx motor is 4,300 miles) despite the track day and longer drain interval of 5,000 miles.

Using AMSOIL will not invalidate your warranty. Depending on the year, your owners manual probably states to use an oil meeting GM Standard 4718M which several AMSOIL oils meet, or for newer GM cars it may say to use only API Starburst Certified oils. 

These AMSOIL products meet GM Standard 4718M:
AMSOIL Series 2000 0w30 (what I use in my 06 CTS-V)
AMSOIL SAE Synthetic 5w30
AMSOIL SAE Synthetic 10w30

These AMSOIL products meet GM Standard 4718M and are API Starburst Certified:
AMSOIL XL Synthetic 5w30 (I use this in my wife's Chevy Trailblazer)
AMSOIL XL Synthetic 10w30

For those that chose the better oils out of the first group, such as I do in my CTS-V, your warranty states that use of aftermarket products will invalidate your warranty only if the failure is caused by that product. For example, my 03 F350 recently had a rocker arm fail. Been using AMSOIL in the motor for years. The oil did not cause the failure and Ford gave me a brand new motor under warranty. If your motor fails and GM says the failure was caused by the oil, and you are using an AMSOIL product recommended for your car, the AMSOIL Corporate Warranty will apply. Either way, you are covered.

On the lines of what bothers me about Royal Purple is that I can't tell if they do or do not comply with the new more restrictive API SM/ISLAC GF-4 standards. I spent 30 minutes surfing their website again this morning and this is all I could find:
"Royal Purple's motor oils are API certified and will not void new car warranties."
"Royal Purple Motor Oil is specially formulated multi-viscosity and straight grades for use in gasoline and diesel engines of all types - from cars and trucks to SUVs, motorcycles and boats. API / ILSAC Certified."

In both cases they imply that they are API Certified to the current spec, but they don't actually say that. 

I did not make any comparisons between AMSOIL and Redline, which is another whole discussion. This thread is about AMSOIL and Royal Purple and all I stated above is how little information Royal Purple provides on their website.



auGTO said:


> Then you state Amsoil has test vs. Royal Purple and Redline, but on the corp. website there is no test comparing them. You are looking at the dealers and the corp. was forced to remove it because they were looking at a lawsuit if they kept false information on their website.


I did not state anything about AMSOIL vs Royal Purple and Redline, only AMSOIL vs Royal Purple, again the topic at hand. I did link to tests on my own dealer website, but that was only to try to prevent loss of customers who go straight to the AMSOIL Corporate Site and make a purchase which will be referred to a random local AMSOIL certified dealer in their area. I'd rather the sale was referred to my dealership which also benefits the forum. That said, all the tests I have on my deaership are in fact also on the Corporate website contrary to your belief. Here are the same links I pasted above, but directly to the AMSOIL Corporate website:
AMSOIL Series 2000 20w50
AMSOIL Motorcycle Oil “White Paper” (1 MB pdf file)



auGTO said:


> The most false test Amsoil has put out is the 4-ball wear test. This test is not for comparisons of different oils from different oil companies, but the same batch to ensure the viscosity is the same and the additives are even distributed through out. Amsoil has taken this test and made it a big selling point, but even they do not know how to run a proper test. It is like the show “Are You Smarter Than a 5th Grader?” Amsoil would fail science. In a test you compare the same, but Amsoil does not. For Example Amsoil uses their racing oil 20w50, but uses Mobil 1’s European oil 0w40 and never even states what they chose from Royal Purple. for all you know it could be a 5w30 or 5w20. How is this a true test when they use a test that is made to test same batch in the same company and they do not even use the same viscosity for all the oils tested?


I'm not sure where you get this info. Whether the 4-ball wear test is applicable to how an oil performs in an oil is debatable. Personally, and this based on used oil analysis reports I've reviewed on another website, I do believe that there is a correlation, and I'd rather use the oil with the lower wear. As for using different weights, or not stating the weights, I disagree. Take a look at the 4-ball wear test on the link to the Corporate Website 20w50 I pased above. All the oils are clearly labeled as to what they are, and they are all 50 weight oils. 

Peace. :cheers


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