Larry B.

I find this interesting... The GM spec GM4718M is on the mobil 1 5W30 qt. containers. It is not on the mobil1 10W30 containers. However... On the Mobil web site, they state that 10W30 Mobil 1 oil does meet the GM 4718M spec. So if you use Mobil 1 10W30 instead of 5W30, the fact that the spec is not on the container AND the owners manual only recommends 5W30 could give GM a reason to deny warranty work.. Why would the spec not be on the 10W30 container when the product does meet the spec.?

jabez

Its the same way with Pennzoil Platinum. 4718m cert on one and not the other.

91C4

5w-30 says it meets Corvette & Viper standards but like Mobile! it's not on the 10w-30 bottle. I guess because the manual says use 5w-30 . But man it's hot here in the soulth and I have never used 5w in my 58 years.

2KFRC5

This is what is in my Vette. Notice "Green" cap. I bought this oil prior to the introduction of the new Mobil oils.

Larry B.

The new 10W30 doesn't have the spec on it. I was hoping someone had an older version.

Moval49er

The GM spec also includes fuel mileage as part of the requirements - 5W30 is a bit better (like 1-2 mpg) for efficiency. Of course, your motor is toasting nicely...

I'm now thinking the hot ticket will be the new extended life 5W30 (still with 5000 mile changes), and a new "stat and radiator to manage temps.

MitchAlsup

As noted in the general section: the operating viscocity of 10W-30 is exactly the same as 5W-30:: both are 10.0 centiStokes of kinemetric viscocity. So the milage will be no different between 5W-30 and 10W-30.

At cold start the 5W-30 has minimaly lower viscocity (56 cSt versus 62 cSt) and after a few seconds the viscocities will not be usefully different. At -10dF the thinner 5W-30 might enable starting a fraction of a second faster than 10W-30.

Running hot these two oils are also equivalent with HTHS numbers of 3.08 (5W-30) and 3.17 (10W-30), and both are a "little thin" for track use. RedLine and AMSoil and a couple others have xW-30 oil formulations with HTHS numbers in the 3.6+ range and are better for this application.

The 1-2 MPG differences are when compared to an oil with an operating viscocity of 14 cSt and a cold startup viscocity of 90-100 cSt--like any general 10W-40 or 5W-40.

NEO1

Amsoil has recently lowered the HTHS numbers down to where Mobil 1 is now, which is 3.2. They gave in to CAFE and fuel efficiency.

LS WON

5w/30 . The extended versions do not meet the specs for the Corvette. Check each bottle and that oil is the only one that mentions this 4718 code.

MitchAlsup

Aggggggg-this is horible:: but good to know another oil not to use at the track.....