Oil Viscosity
Thread Starter
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Oil Viscosity
Looking at a comparison of several synthetic oils (both 5W30 &10W30) and the viscosity at 100 degrees "C" vary from 9.9 to 11.0 cSt per ASTM D445 (at least those that list the test standard denote D445). I am not an oil expert but am looking at what synthetic to use in my new car. Also, some of the oils that I am looking at have not been tested to GM 4718M. If I look at the range in value of the viscosity at 100 degrees, doesn't this give a good indication of how well the oil works at elevated temperatures? It would seem to me that an oil with a viscosity value near the high end (11) would provide better lubrication and protection then the oil at the low end (9.9). Am I evaluating this correctly?
Melting Slicks
Joined: Jul 2000
Posts: 2,483
Likes: 1
From: Wilmington DE
Re: Oil Viscosity (vettenuts)
You are correct if everything else was equal, but from brand to brand everything else isn't equal. Higher viscosity doesn't of itself mean better engine protection. If an oil is formulated to have high film strength and resist evaporation then the lighter oil will protect the enging better because of its better properties and more rapid circulation will deliver better cooling to the engine. This better cooling is extremely important, sine oil flow furnishes up to 30% of an engine's cooling requirements. Just make sure the oil you use meets GM Spec. 4718M. Hope this helps. :D
Thread Starter
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Re: Oil Viscosity (Jerry Velders)
Guess I am just examining the alternatives. Right now, it appears that Mobil-1, Amsoil and Royal Purple are the only ones that I would consider that also meet GM4718M.
Melting Slicks
Joined: Feb 2000
Posts: 2,375
Likes: 0
From: Pittsburgh, PA
Re: Oil Viscosity (vettenuts)
Check out the performance of Pennzoil fully synthetic with Pennzane. The specs are impressive and superior to Mobil One and Amzoil. I run it and like the fact that it does not turn dark like the Mobil One did after a few hundred miles.
Drifting
Joined: Sep 2001
Posts: 1,421
Likes: 3
From: Memphis Tn
Re: Oil Viscosity (vettenuts)
From a previous thread Royal Purple doesn't carry the starburst symbol of certification, which could give your dealership a good excuse to void your warranty if they knew. :seeya
Thread Starter
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Re: Oil Viscosity (ScreaminDemon)
In the end I went with Amsoil. It is API certified, and the viscosity at 100 degrees C is higher then that of Mobil-1, Royal Purple and Redline. It also meets GM4718M. The specifications on the oil appear to be the best of all of them plus it has been thoroughly tested. I feel comfortable with this decision. If I went to Redline, even though I think it is a good oil, the testing simply doesn't exist to back it up and I didn't feel comfortable using it for this reason.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski