Let's not start the usual 'oil thing' but living in S.W.Florida
many of My local corvette club members are telling Me...."Use 10-30
in this hot weather the 5-30 is too leaky...any thoughts?

 

Vert has 20,000 on it, so here in the hot weather I use 10-30.

 

If you have a seal or gasket that is compromised, it doesn't matter which oil you choose....it leaks.

 

I use Mobil-1 0W30. Works great, better mileage by 6% or so

 

i thought that the first number was the winter weight and the rating only mattered at 0 degrees. here in FL the first number shouldnt matter only the second.

 

Next time I change the oil, I will probably go with 10-30.

 

If you're using Mobil 1, their 10w-30 is actually thinner than their 5w-30 at operating temperature.

 

I believe that I have 10w30 in mine.

 

 

 

And where did these geniuses get their Chemical Engineering degrees? Think their brains are leaky.

 

Technically, at operating temperatures 5-30 and 10-30 are identical. That is, at operating temperatures they have a viscosity that is equal to that of a 30 straight weight oil. Similarly, cold the 5-30 has a viscosity of a 5 weight oil and the 10-30 has the viscosity of a 10 weight oil. Using 10-30 over 5-30 is a bad choice as the 10-30 oil is thicker at start up, something you don't want with the LS engine.
I run 0w-40 royal purple, great viscosity for start up and great viscosity for the summer months, which are the only months the car is in service.

 

Check the viscosity at 100*C and I think you will find Mobil-1 of either viscosity is near the bottom of the 30W range. German Castrol 0W-30 is near the top, which is why I run the German Castrol.

 

I am in Virginia and have always run the 10w30.

Remember that the larger the range is, they have had to put viscosity modifiers in the oil, which can fail. If you are running in warm climates then your oil may never get to the lower number i.e.

@ 0 degrees viscosity is 5
@ 50 degrees viscosity is 10
@ 100 degrees viscosity is 20
@ 190 degrees viscosity is 30

These are made up numbers, but that is how the oil works. If your are in Florida, I doubt your car is ever below 50 degrees. GM even recommends the 10W30 in warm climates.

 

I guess you consider a "warm" climate above zero...

 

I can never understand why there are some who insist on trying to improve on something that is time tested and proven. The engineers who devoloped the LS engine designed it to go for about 200K miles so it would stand to reason that the engine oil plays the most important role in achieving this goal. Mobil 1 5W30 has been the recommended oil for the LS engine from the start of the C5 run and remains so to this day with the C6. If there was any issues with this oil (brand or grade) I'm sure they would have revised the oil requirements by now. Yes the manual says you can run 10W30 when 5W30 is not available, but it does not say to use it instead because it's better for the engine. The Engine can also run on 87 octane when 92/93 is not available too, but not recommended in place of. Then you have the conspiracy theroists who say GM says use Mobil 1 simply beacause Mobil pays GM to say so. They most likely do and they should because they sell a lot more oil because of it, but thats not the only reason that GM and a lot of other high end auto makers use it, perhaps they use it because it works. From experience I can say that Mobil 1 5W30 has been in my Vette from day one (I'm the original owner) and 77K later the engine runs just as well as it did when I first drove it home from the dealer. And I just like the majority of other Corvette owners drive their cars mostly during the warm weather months a lot more than sub zero weather, I can assure you. The bottom line is it's your car and you can put in sewing machine oil in it for all anyone cares, but do yourself and your car a favor and stop trying to reinvent the wheel. Do what the engineers who made the thing says to use and don't worry about it!

 

What he said....

 

Please show me where you found the above statements, in blue, in either the Owner's Manual, or the shop manual. I can't find them.

Thanks,
Don

 

Open your owners manual and go to page 6-14 and 6-15 and it's under "What kind of engine oil to use".

 

I still can't find where it says to use only Mobil 1. I can only find that it says to use oil that meets GM4718M. And the viscosity doesn't say to use 10w-30 only if 5w-30 isn't available. It says that you can use SAE 10W-30 if it’s going to be 0F (-18C) or above.

Nowhere does it say on my oil filler cap that Mobil 1 is recommended, only that Mobil 1 is what they used for the factory fill and to see the Owner's Manual for the special oil requirements.

Don