5W-30 vs. 10W-30?
Le Mans Master
Joined: Nov 2003
Posts: 8,004
Likes: 250
From: Tampa Fl
St. Jude Donor '12-'13-'14
summer and winter blends WTF 
I put on 3500 miles last year and 2500 miles this year
I stick with the Generals orders
I put on 3500 miles last year and 2500 miles this year
I stick with the Generals orders
Last edited by phils C5 vette; Jan 8, 2005 at 04:32 PM.
Race Director
Joined: May 2001
Posts: 15,324
Likes: 2,080
From: Guelph, Ontario
Originally Posted by Pumba
Ron,
I thought because I do not drive in the winter I would switch to Mobil 1 10W30 when I purchased my Z06.
After reading what Mobil hase to say about their 0W40 European Mobil 1 I have switched to it. It offers the benefit of 0 viscosity at startup and can thicken to 40 weight as the crankcase temperatures elevate.
Good luck with your decision.
I thought because I do not drive in the winter I would switch to Mobil 1 10W30 when I purchased my Z06.
After reading what Mobil hase to say about their 0W40 European Mobil 1 I have switched to it. It offers the benefit of 0 viscosity at startup and can thicken to 40 weight as the crankcase temperatures elevate.
Good luck with your decision.
The second number is it's viscosity at 100c. To be a 30 weight, it must be between 9.3 and 12.5 cst at 100c. To be 40wt it's 12.5 to 16.3.
An oil that is a 0w40 will simply not thin out as much when hot as a 0w30 oil.
The German made Castrol 0w30 is almost a 0w40 oil, because it's viscosity is 12.2 cst at 100c. Mobil 1 5w30 and 10w30 are both very thin 30 weight oils at only 10.0 cst. Which is why they aren't the best oil choice for cars that see high oil temps (keep in mind, the hotter the oil gets the thinner the oil gets, so your oil is very thin at 300F!)
