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Changed Mobil 1 oil specification for C7

Stingray

CCCUK Member
#1
Well this took me a little by surprise. Back in the day US oil spec Mobil 1 for Vettes was 5w-30 but the oil wasn't available in UK and there was a lot of debate around what to use. I was one of those who didn't fret too much and simply used the available 0w-40.

My Stingray is due for an oil change and Halfords are currently offering their usual early Spring 20% discount on Mobil 1. But the range of available oils has changed and now includes a wider selection of grades. My driver's handbook recommends 5w-30.

But check out this link to Mobil 1 website!!
Chevrolet Corvette recommended oil | Mobil™ Motor Oils

"Mobil 1™ 5W-30 is the recommended service fill for many generations of Corvette, but for all C7 Corvettes we recommend upgrading to Mobil 1™ ESP Formula 0W-40."
 

Rich

Administrator
#2
I am about to open a can of worms and can do no better than repeat a post from someone else from the old website in 2011. Of course the oil recommendations may have changed since then. My advice would be to get a definitive answer form Ian Allan Motors as to what oil they use.

"As you probably know, for Corvette C5s the GM recommended oil in the handbook is Mobil 1 5W-30 which conforms to specification GM4718M. This has not been commonly available, so with approval from GM, most folk, including me, have been using Mobil 1 0W-40.

My oil change was due and I was pleased to find on Halford's shelf, Mobil 1 ESP Formula 5W-30. At last, the right grade, off the shelf I thought. I duly bought some but before installing, as there was no mention of GM 4718M, I thought I'd check with Mobil 1.

Their response was as follows. "Unfortunately Mobil 1 ESP Formula 5W-30 doesn't meet GM 4718M specification. GM 4718M is a specification required only for GM, Chevrolet & Corvette cars made in USA and therefore we have a number of engine oils with such spec in the States but in Europe we only have Mobil 1 0W-20 and Mobil 1 5W-30 (in Russia only), due to limited presence of such cars. As far as I know Mobil 1 ESP 0W-40 is the best solutions for cars requiring GM 4718M, yet it doesn't meet it so I would use it after warranty only. Going for Mobil 1 0W-20 may be risky in your car because it's too thin even if it meets GM 4718M."

Following on from this I checked with GM UK and this is what they had to say.

"GM have developed the DEXOS brand of oil across the world. In the US, DEXOS 1 is only avail and meets all the GM Gasoline
requirements, today and retrospectively. In EU, DEXOS 1 is not sold, but DEXOS 2 is , and this DEXOS 2 oil meets the
Diesel requirements AND GM Gasoline requirements, inc. Corvette C6 and
older models.

Quote from GM Bulletin #11-00-90-001: Global Information for GM dexos 1 and
GM dexos 2 Engine Oil Specifications for Spark Ignited and Diesel Engines,
Available Licensed Brands, and Service Fill for Adding or Complete Oil
Change - (Mar 14, 2011) ,
"
dexos 2™ is approved and recommended by GM for use in Europe starting in model year 2010 vehicles, regardless of where the vehicle was manufactured.

dexos 2™ is the recommended service fill oil for European gasoline engines.

DEXOS 2 is avail from Vauxhall/Chevrolet Dealers."

And so folks, it looks as though GM are now telling us to use Dexos 2 as service fill. I returned my £50 a gallon Mobil 1 and bought some genuine GM Dexos 2 5W-30 from my local GM dealer. It seems to meet most of the grades of the Mobil 1 0W-40 but additionally it has the all important GM approval. And yet, it cost me jus £18.00 a gallon. Work that one out if you can. Have I misread the situation or has anyone anything to add? Thought you'd all like to know."
 

Stingray

CCCUK Member
#3
Things move on and, as it happens, the 0w-40 and 5w-30 currently on sale at Halfords are both Dexos 2 compliant. For some reason the 0w-40 is a couple of quid more expensive than 5w-30 so perhaps that's what Mobil mean by an "upgrade"!
 

Norm

CCCUK Member
#4
What ever that owner's manual recommends for that year engine, I stick with, can't go wrong. That's all I use, Mobil 1 5W-30.
 

teamzr1

Regular user
#5
Frankly the street driving oil GM specs is really for better fuel mileage and nothing else
You notice themselves GM states for racing use like a 15W50

Stick with the Mobil I as all the seals, O-rings, gaskets, etc were matched at design stage to function well with Mobil 1 synthetic

I have use mostly 10W30 for street and 15W40 ( since my new 1984 C4) for racing the lower weight like 0 or 5
will become blowby and can reverb back out through aircleaner.
 
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