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Discussion Starter · #1 ·
Hello all,
I'm interested in what everyone is using for oil, tranny, rear diff and any other fluids I haven't thought of. If you believe what you read then everything is the best to use! I've got 2500 on mine and will be changing the oil for a second time soon, maybe it's time to upgrade all the fluids? I don't race mine and generally drive sanely but I'm also not afraid to wind it up. Suggestions?

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363 Posts
I am an Independent AMSOIL Dealer, so please feel free to take this with a grain of salt.

Two years ago, during my first season, I lost a $5500 LS6 motor due to a seized bearing. Shortly thereafter I spent about a month researching the various oils, including reading hundreds of used oil analysis reports and dozens of independent lab tests. Redline and AMSOIL consistently performed at the top of the list. Royal Purple didn't fair very well in the used oil analysis reports I reviewed. Redline uses an ester based synthetic that had a bad reputation in many circles, particularly for synchronized gearboxes. AMSOIL uses a PAO basestock (which Mobil 1 now uses as well). Ultimately I chose AMSOIL and have been running it for the past two seasons and I'm very happy with its performance. I didn't become a dealer until after switching to AMSOIL when I found out that with a dealership I could offset some of my racing expenses.

I have used oil analysis reports from one of my own customers running an LS1 Corvette C5. The results show what I expected. AMSOIL uses much higher levels of anti-wear and detergents than other oils and the wear results showed it. The wear metals for his motor are about 25% of the universal average for that motor type for that lab.

AMSOIL has begun including Royal Purple in its independent lab tests. AMSOIL recently completed one with motorcycle oils:
Motorcycle Oil Comparison

The applicable AMSOIL products for a 2005 GTO:
Motor Oils:
AMSOIL Series 2000 0w30
AMSOIL SAE Synthetic 5w30
AMSOIL XL-7500 Synthetic 5w30
Oil Filter (SDF32 is the correct part for the LS2):
Tranny fluid:
Diff fluid:
AMSOIL Severe Gear Extreme Pressure Synthetic 75w140

I find this comes in handy:
AMSOIL Hand Pump

Request a Free AMSOIL Catalog
AMSOIL Ordering Information
AMSOIL Preferred Customer Program

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410 Posts
I've got RP in the engine, tranny, and differential. I'm very please overal. RP Syncromax in the tranny works great - much smoother. Got a friend with a Vette that used Amsoil ATF with good results. RP GearMax worked great in the differential and did not require any modifiers - a big plus. I wouldn't hesitate to use these products.

For the motor oil, I've written and called RP and asked for the HTHS (High Temperture High Stress) rating for a comparison becuase I have heard of some issues with not as good engine wear with RP. Have not heard back from them. I believe RP is much better than conventional oil but if the HTHS rating doesn't come back at 3.0 or better, I'm going switch to Amsoil 0-30.

I went with the RP because or good reports and I can get it at my local NAPA dealer anytime I want to (don't have to order or wait for shipping)
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