Tried doing a Google search for 5w40 and c6. Didn’t really come up with much.


just curious if any of you are using 5w40 instead of 30?

I don’t really see oil temps all that high. Maybe 230.

but when I check dipstick at that temp the oil is basically water on it.

so curious if I should switch over to 40? For a bit extra cushion at higher oil temps.

 

Why would you go against what the engineers who designed the engine say you should use?

 

Put in the Mobil1 5w30 with a good Wix filter and forget about it until the next oil change

 

To get more than 25 points spread in a synthetic oil you have to add viscosity modifiers to it which are the first thing to break down. No real advantage.

 

I use Royal Purple 5-30W but there are a few choices out there as others have mentioned, Mobile 1 is a good choice also.

 

Current thinking is that you don't need thicker oil in a modern car that is running correctly.
I doubt that it would be a problem, but I also don't see any advantage.

 

 

Your interpretation of "basically water" is a fallacy. Oil used to get thick and sludgy quickly. We looked on the dipsticks back then, and thought that is what oil is supposed to look like. Things have changed greatly. Engine tolerances are much finer. Engines now go 300K miles, whereas back then, any engine that went 100K was rare.

The oil you have in your car is exactly what it needs. Do not mess around with something that engineers spent decades perfecting.

 

First, engineers do not make final decisions, not even at NASA. They work within given constraints.
Second, Mobil 1 is on your engine oil cap because Exxon Mobil pays to have it advertised there.
I believe that those statements are facts. The following is my opinion.
Manufactures and engineers recommend the lightest oil that will still get you past warranty and what is generally socially acceptable (125K to 175K).. Lighter oil means less resistance and better mpg for the car and fleet.
In the not so distant past, cars were beginning to regularly hit 200K, 300K and more miles. Clearly "overengineered." So, the government take the zinc out of the oil and the manufacturers and engineers lower the viscosity to reach fleet targets. Cars get better mpg and pollute less and most still reach 150K or so. Win win for everyone that wants to drive the car under 200K and that is most everyone.

Could you go with a 15-40 for diesel cars? I don't know enough about the design changes to allow for very low viscosity oils to know. I wish there were someone in the system that you could trust for empirical facts.

 

I ran mobil 1 0w-40, which is just barely thick enough to be 40 weight, for a little while last year. It seemed to quiet down the valvetrain a tiny bit. I'm currently running mobil 1 esp 5w-30, which is a thick 30 weight. There's some evidence that the mobil 1 esp 0w-40 designed for the LT1 is backwards compatible

There's quite a few guys on LS1tech running 40 weights

 

I honestly feel like this is ++++.


All these people saying “do what the engineers said”.

they get paid by Mobil 1.

and they get paid by repairs. Not cars being bought...

 

No, Mobil is not the ones that put that information in your owner's manual. If you're not going to do ALL of what the owner's manual says, why do any of it?

Don't post anything here if you have troubles with your car from the oil in a few years after changing.

 

My daily driver, a Ram 1500, asks for 5w20. I use 5w30 with no issues and I predict the motor will last longer because of it. My point is, if it's your car, put what ever oil you want in it. I wouldn't be concerned about putting 5w40 in my car.

 

https://www.chevrolet.com/content/da...ion-guide-.pdf
From GM about what oil to use in what engine. You'll notice that for e-rod engines the first recommendation is 0w-40. E-rod engines can be LS3's, the difference being they don't have to pass the stringent emissions and fuel economy tests of newer cars. I'm not saying the 0w-40 is necessarily better, but I don't think it's going to break anything

 

The OP could try this; Be conservative and use only half a quart at the next oil change:

 

Oil is oil. Viscosity DOES make a difference, but it’s engine-to-engine results. I owned a Bonanza with a Continental 520. Everyone said to run the multi-weight, but I found that running straight weight 50W whenever the temperature outside allowed reduced my oil consumption to zero - AND I ran the engine about 600 hours over TBO.

That said, modern synthetic oils don’t break down - they get dirty. So you change oil MOSTLY because of the dirt, NOT because the oil destroyed itself like in the old days. SO - consider simply adding a filter change to your maintenance schedule every 25-33% of oil life, as noted on your instruments. It will put a clean filter in your system and dilute your dirty oil by about a quart. In my Z06 with 10 qts oil, that’s less of a dilution, but in your C6 with normal oil capacity, you would get more effect. And the clean filter will still be there.

Modern Corvettes don’t live at high revs; instead they use torque and low revs to deliver decent gas mileage. If you’re tracking your car then 0-viscosity makes sense to better protect a race motor at start-up and 40W makes sense at the revs the race motors live. But for street use, CLEAN oil is more of a factor than viscosity. My opinion, and my engineer friend from Standard Oil. YMMV.

 

0w-40 M1 is what is the C6 spec in Europe, Why 5w-30 here? i use 0w-40

 

I agree. I been using 0w-40 for quite a few years.

 

As the other posters said, use 5w-30 & don't overthink it

 

I agree for street use, but since I started doing HPDE, others including myself have changed due to the higher zinc which translates to less wear.
Also with higher oil temps on the track, it is highly recommended.