Engine Oil Choices 5W30 or 15W40?

[55Designs]

I am ready to change the oil its 1100 miles now.

Some guys are using the 5W30 and some guys tell me use 15W40 Rottella.

I use the Rotella on all my vintage stuff but I wanted to hear some opinions of using it on the LS3 at such low miles.

[Russell James]

The right answer is in your owner's manual and on your oil cap. 5w30 synthetic. Or, 10w30 optional for warmer climates. 15w40 is for diesels.

[HeavyD]

15W40 is for big diesel engines, don't use it in your LS3, too thick. Your engine calls for synthetic oil, that is what you should be using! Go with 5W30.

[Jekyll-N-Hyde]

Rottella Not in a gasoline engine car !!!!!!!!!!!!!!!!

Stick to the owners manual.

[TommyTSquared]

Originally Posted by 55Designs

I am ready to change the oil its 1100 miles now.

Some guys are using the 5W30 and some guys tell me use 15W40 Rottella.

I use the Rotella on all my vintage stuff but I wanted to hear some opinions of using it on the LS3 at such low miles.

Some guys don't need to be listened to.

[Beyond Limits]

Don't ever let some guys near your car... Rotella oil is Diesel engine oil. Because of the way diesel engines use oil (cooling of the high pressure diesel injection lines for example), and the demands that modern diesel engines put on oils (significantly higher sheer loading, much higher oil pressures, soot loading, and sulfur content in diesel) these heavy service oils (Rotella and Delo 400 for example) are not even close to being a correct lubricant for any gasoline engine.

Although... in an LS3 Rotella or Delo 400 would be a lifetime oil... the only oil you ever need since your engine would not make it to the next scheduled oil change...

But don't my word for it... ask an Amsoil guy...

[The_Blur]

When it comes to oil, only do what your manual and Camaro5 tells you to do.

[axis]

Rotella works great in our turbine engines on the helicopter too.

[kelleyperformance]

yeah rotella is a bad idea in a gas engine. i wouldnt ever go with a higher viscosity in an LS than 10W-30, ever. the thicker the oil, the less that actually makes it through the pick up into the pump and into where it needs to be. people often confuse higher pressure from use of a different oil good... when in fact all it means is reduced oil flow =

[OUR72GTO]

Did you read the owners manual?

" Some guys" at GM helped write it...... Others call them engineers.

[SicSix6]

Originally Posted by Russell James

The right answer is in your owner's manual and on your oil cap. 5w30 synthetic. Or, 10w30 optional for warmer climates. 15w40 is for diesels.

+1. Read the manual

[thesnoopster]

I think the person who told you to use that oil is probably jealous of your car or a Camaro hater and wants your car to croak....LOL

Go with what the manual says

[Gokhan]

Using 15W-40 or diesel-engine oil will not harm your engine. Modern diesel-engine oils fall into CJ-4/SM category, meaning they satisfy all API requirements of all time for both gasoline and diesel engines. Diesel oils have better additive packages than the gasoline oils -- to put it simply they are better oils. In fact most good synthetic oils also have the diesel "C" certification. The only possible caveat is that they have a high concentration of detergents and they will extra-clean your engine, which may change the way it runs by removing the carbon deposits around pistons and cylinders and varnish deposits around other parts, therefore changing the clearances. Engine may readjust to new clearances but you shouldn't change back and forth between CJ-4/SM and SM (diesel/gasoline and gasoline-only) oils.

Thicker viscosity will usually not harm your engine. In fact, simply put, thicker the oil, more protection on the metal parts, including less wear. But it will reduce fuel economy and horse power -- that's the primary reason why car makers recommend thinner oils nowadays. Also, in very cold areas, you should use 5W-30 oil in winter, otherwise the car wouldn't start or run probably when it's cold.

But the truth of the matter is that the most important thing in an oil change is the oil filter. Virtually all oils are good nowadays, whether it's gasoline or diesel, thin or thick, synthetic or conventional, but with most oil filters, especially the OEM ones, they will turn into mud after a few weeks in a running engine. When this happens, oil thickens and the viscosity becomes more like 20W-50 or above. Therefore, it's crucial that you use a top-quality oil filter -- it will make the difference. I use Purolator PureOne and I'm very satisfied with it. It filters 99.9% of the contaminants according to ISO tests.

In summary:

• Oil thinner than recommended (such as 5W-20) will harm your engine because it won't have enough protection recommended for your engine.
• 15W-40 oil will not harm your engine in warm climates because it will have more protection than recommended for your engine. But it will decrease your fuel economy and horsepower.
• Diesel oil will not harm your engine if it also has gasoline (SM) certification, as it's the case with most diesel oils now.
• It's not a good idea to switch back and forth between gasoline and diesel oil, as they have different detergent levels, with diesel oils cleaning your engine and gasoline oils letting some carbon deposits and varnish build up -- therefore clearances changing back and forth.
• It's probably not a good idea to switch back and forth between thin and thick oil either
• You're usually OK with the manufacturer's recommendation (5W-30)
• Most importantly but unfortunately most often neglected, use a top-rated oil filter such as Purolator PureOne (99.9% efficiency) -- otherwise no matter what kind of oil you are using, it will turn into mud after 1,000 miles, and it won't make a difference how good oil it is or how thin it was originally because it will get thick and contaminated and lose it's protective effectiveness. OEM filters are junk because they are designed for very long service intervals and tend to be undersized to comply with waste-management requirements, these two conditions together constraining them to have very low efficiency, therefore letting contaminants build up in the oil. But with high-efficiency filters like PureOne, make sure to change your oil every 3,000 miles so that the filter doesn't clog and open its bypass valve.
  

[thekid96]

The Rotella oil line is available for gasoline engines as well as diesel, synthetic and non. While the rotating tolerances on the LS engines are set for a 30 weight oil there are other considerations when choosing an oil. The published oil weight is based on an operating temperature, in this case 200-210F. As oil temperature increases the effective oil weight decreases, in other words a 30 weight oil will have the same viscosity as a 20 weight at a given (higher) temperature. A 40 weight oil has the potential to damage bearings at normal operating temperatures by creating more bearing film. However, at elevated operating temps, such as at the track, a 40 weight oil might offer better operating conditions.
In the end understanding the nomenclature and how the oil functions in a given environment is most important.