which oil should i run
"AlohaC5" Senior Member
Joined: Jun 2003
Posts: 3,562
Likes: 44
From: Madison, AL
Its my understanding the 1st number is the weight of the oil while operating in lower temperatures (Winter) while the 2nd number indicates the weight of the oil while operating at higher temperatures (Summer). That's why many drivers change to German Castrol 0W30 (actually closer to 40 weight) or Mobil 1 5W40 because of the higher viscosity while participating in HPDE/TT events during the Summer. Bobistheoilguy.com said the Mobil 1 5W30 actually protects at a 20 weight level at higher operating temperatures. Not all synthetics are made the same.
Last edited by Gray Ghost GS; Jun 12, 2006 at 10:44 PM.
Race Director
Joined: Jul 2004
Posts: 16,795
Likes: 62
From: Lake Havasu City, AZ
5W30 is fine.
Going to higher weights is old school thinking based on the need to go to more viscous oil to get the film strength.... not an issue with synthetics
Many race teams are running 0W30
Better lubrication, more gas mileage, more horsepower
Going to higher weights is old school thinking based on the need to go to more viscous oil to get the film strength.... not an issue with synthetics
Many race teams are running 0W30
Better lubrication, more gas mileage, more horsepower
Drifting
Joined: May 2002
Posts: 1,607
Likes: 1
From: San Francisco CA
If you’re not using oil between changes and don’t see sustained oil temps above 225 then 5w-30 should be fine, otherwise use 10w30 provided the outside temp is above 10 degrees. If you really drive the car hard for prolonged periods then you may want to consider 15w-50. Regardless of what weight oil you end up using, I would choose Mobil 1 Extended Performance over regular Mobil 1 because it’s a superior oil in all respects.
German Castrol 0w-30 is also superior to regular Mobil 1 5w-30; I haven’t heard how it stacks up against Mobil 1 Extended Performance 5w-30.
German Castrol 0w-30 is also superior to regular Mobil 1 5w-30; I haven’t heard how it stacks up against Mobil 1 Extended Performance 5w-30.
Le Mans Master
Joined: Oct 2001
Posts: 5,577
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From: Southern Maryland Maryland
Race Director
Joined: Mar 2001
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From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
Originally Posted by Phil97SVT
Amsoil is the top dog...just look at the results of the tests. 
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Melting Slicks
Joined: Jul 2005
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From: Rehoboth MA . . . NRA Life Member
St. Jude Donor '06-'07
Originally Posted by Phil97SVT
I run AMSOIL 5W40 full synthetic in my Z06..
Bob
Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
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From: King George VA
Originally Posted by rws.1
5W30 is fine.
Going to higher weights is old school thinking based on the need to go to more viscous oil to get the film strength.... not an issue with synthetics
Many race teams are running 0W30
Better lubrication, more gas mileage, more horsepower
Going to higher weights is old school thinking based on the need to go to more viscous oil to get the film strength.... not an issue with synthetics
Many race teams are running 0W30
Better lubrication, more gas mileage, more horsepower
Originally Posted by SFVetteman
German Castrol 0w-30 is also superior to regular Mobil 1 5w-30; I haven’t heard how it stacks up against Mobil 1 Extended Performance 5w-30.
Used Oil Analysis Comparison: German Castrol 0w30 vs AMSOIL Series 2000 0w30
You can draw a fair comparision of German Castrol 0w30 vs Mobil 1 EP 5w30 using that data and this test:
Comparative Motor Oil Test
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Instructor
Joined: Feb 2005
Posts: 219
Likes: 0
After spending 4 years at BITOG, I do not think Amsoil is the best choice for this engine. German Castrol has been by far more consistant then any of the Amsoil grades. Terry Dyson, a Tribologist will tell you the same. He will also tell you to run Redline in this engine. Oil analysis doesn't always give the most accurate measure of determining engine wear. Amsoil has also lowered the High Temp / High Shear of the 0w-30 TSO oil to 3.2 The product data sheet is out dated and from over a year and a half ago.
A guy buy the name of sgtgeek tried this oil in his modified GTO and it didn't perform well at all. In fact he switched back to Shell Rotella I believe. Realize that the 4ball wear test is misleading. There are guys running Redline 5w-20 with great results in C5's. While amsoil is not a bad oil, it is not the best choice for high performance cars. If you use any, I would use the 5w-40 AFL, although Mobil 1 SUV has been probably the best performing oil on bobistheoilguy.com if one does a search.
A guy buy the name of sgtgeek tried this oil in his modified GTO and it didn't perform well at all. In fact he switched back to Shell Rotella I believe. Realize that the 4ball wear test is misleading. There are guys running Redline 5w-20 with great results in C5's. While amsoil is not a bad oil, it is not the best choice for high performance cars. If you use any, I would use the 5w-40 AFL, although Mobil 1 SUV has been probably the best performing oil on bobistheoilguy.com if one does a search.
Instructor
Joined: Feb 2005
Posts: 219
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I actually spoke with an Amsoil technical service worker and he did emphasize that Amsoil is more of a "extended drain oil". The Series 3000 oil is more ideal for this engine then the Series 2000 I believe. Higher amounts of Zinc and Phosphorus and loaded with Calcium. The German Castrol is what I would use. It has a High Temp High Shear of 3.6. This number isn't as important as most make it out to be, but for extremely hard driven vehicles, it does come into play.
Premium Supporting Vendor
Joined: Aug 2001
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From: King George VA
Originally Posted by NEO1
After spending 4 years at BITOG, I do not think Amsoil is the best choice for this engine. German Castrol has been by far more consistant then any of the Amsoil grades.
Haven't heard from you in a while. How's life?
Here is a used oil analysis comparison from a fellow forum members 99 FRC showing that AMSOIL matches up just fine with GC:
Used Oil Analysis Comparison: German Castrol 0w30 vs AMSOIL Series 2000 0w30
Originally Posted by NEO1
... A guy buy the name of sgtgeek tried this oil in his modified GTO and it didn't perform well at all. In fact he switched back to Shell Rotella I believe...
"I use Amsoil/Schaffers/Royal Purple and Cosworths over Mobil1. Why? Superior protection/superior detergent,suspension...and superior film strength."
"IMHO Amsoil ATF is the best stuff out there. My trannie temps never rose above 170-180 even after a good flogging. Stuff kept my trannie clean as a whistle to boot. Get what you pay for in life and this stuff is worth every penny."
Safety Car
Joined: Apr 2000
Posts: 3,802
Likes: 61
From: Wichita KS
The current (September 2006) issue of Corvette Enthusiast magazine did a head to head test between Mobil 1 and Royal Purple 5W30 in a 1998 Corvette on SLP's dyno and found that Royal Purple showed a 3.8 HP and a 4.8 Lb-Ft gain over Mobil 1.
All things being equal, why not go with the Royal Purple?
All things being equal, why not go with the Royal Purple?
Team Owner
Joined: Jul 1999
Posts: 50,808
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From: Buy USA products! Check the label! Employ Americans
Originally Posted by CCrane00
The current (September 2006) issue of Corvette Enthusiast magazine did a head to head test between Mobil 1 and Royal Purple 5W30 in a 1998 Corvette on SLP's dyno and found that Royal Purple showed a 3.8 HP and a 4.8 Lb-Ft gain over Mobil 1.
All things being equal, why not go with the Royal Purple?
All things being equal, why not go with the Royal Purple?
not easy to find and $$$$$$$$ for most not racing. LG did find similar results in HP gains with RP which is good when your racing.
Burning Brakes
Joined: Nov 2003
Posts: 790
Likes: 7
From: Denton TX
I concluded some time ago that this question is difficult to answer so I decided to rely on experts. When my 346 was running around 550 Flywheel HP the folks up at Lingenfelter recommended I run Redline 15w 50. When we built the 402 we used the same oil. I should mention that the relief spring in my oil pump has been shimmed up a little.
At idle with a cold engine I get almost 60lbs of oil pressure. When the engine warms up and the oil is at about 220 degrees the idle pressure is about 43lbs. Now a couple of weeks ago I did a track day and my oil temp got as high as 330. At this temp the idle pressure was 27lbs.
What this has made me realize is that much depends on what you plan to do with your car.
At idle with a cold engine I get almost 60lbs of oil pressure. When the engine warms up and the oil is at about 220 degrees the idle pressure is about 43lbs. Now a couple of weeks ago I did a track day and my oil temp got as high as 330. At this temp the idle pressure was 27lbs.
What this has made me realize is that much depends on what you plan to do with your car.