QuickSilver2002

Not considering price, why would you go with 10w-30 instead of 5w-30?

I understand you need 5w when the temp drops below freezing, but is there any advantage to 10w in warmer climates?

My gut says 5w would be better on the engine at startup, even in warm climates.

Thoughts?

MAGRED 02

I have 10w on mine now. Only because it's a little thicker and it really gets hot down here in the summer time. In the Fall I will switch back to 5w.

:cheers:

Dave68

I can't think of any advantage other than possibly slowing down or stopping an oil leak. As stated in a previous post, one person is using 10W-30 simply because it was on sale. Both viscosities can handle the same upper temperature limit.

yelloz06

I am by no means an expert but I have read here and on other forums by folks that have more knowledge than me that the wider the spread, the more VI (viscosity inprovers) an oil has, and this may cause the oil to break down quicker in really severe conditions. Ford is now using 0w20 in new vehicles.

:cheers:

kwik8racr

I have one of the 2001's that burns a little oil,and I put in 10w30 Royal Purple hoping to slow it down, but I havent driven the car enough to know if it has made a difference yet or not.

Jim 47

Guys:

I don't have my old formulation books any more, but the main difference in the 5W and the 10W oils is the percentages of the various base stocks (or light, medium or heavy oils) that are blended together to achieve the starting point of the product. The percentages of additives used in the 5W vs. the 10W are fundamentally the same.

The same thing occurs in blending the base grades of Synthitic oils. There are low Vis. synthetic oils and high Vis. synthetic oils.

The formulation for the 5W-30 engine oils will use a slightly higher percentage of the lighter vis. base oils than will the formulation for the 10W-30 engine oils. Everything else is basically the same.

The higher percentage of the light Vis base oils will give the finished 5W-30 grade more fluidity at low temperatures, and the Viscosity Index improvers that are in both the 5W and the 10W blends will provide the same thickness (or viscosity) at the higher temperatures.

To answer your question, unless you live in a very cold climate, the 10W-30 will be fine for you C5 engine, even in the winter. The real reason that GM puts 5W-30 in the crankcase is that it give them a tiny improvement in gas mileage, especially under cold start-up conditions. I hope this helps. :cool:

QuickSilver2002

Thanks for the good info guys.

So does this mean that 5w is somewhat better, since it will start flowing quicker in cool conditions but matain a good (as good as 10w-30) viscosity at high temps.

NEED FOR SPEED

What it means is that 5-30 is a little better cold and 10-30 is a little better hot.Both are good oil. You make the choice. I run 10-30.

Chifo Jr

Switching to 10-30 in our 02 silenced the dreaded piston slap.

Dave68

I believe that the "30" designation indicates the high-side of the oil's temperature range and is not dependent on the low-side designation. Therefore, 5W-30 oil protects just as well at high temperatures as 10W-30 oil.

vettenuts

I check the viscisity at 100 degrees C. The 10W30 is usually a smidge higher then the 5W-30 of the same brand. However, between brands, there is a larger difference.

Tom/99

I use the 10w-30 here in Texas. For the warmer tempertures, the 10w-30 flows just fine .

IMQUIK

Forget 5&10w30! :cuss
Go with Amsoil Series 2000 0w30 for the best protection out there. :yesnod: :yesnod: :yesnod: :yesnod: :yesnod: :yesnod: :yesnod:

silversport

5W-30 flows better in the bitter cold than 10W-30.
10W-30 is THE SAME (it's the 30 part of the equation) as 5W-30 on the hot.
The improvement is the SLIGHT edge in gas mileage with 5W over 10W.
Some are using 0W-30 but I would hold off unless it is recommended by GM if you are still under warranty...just my .02... :seeya :chevy

yellowy2kc5

Of course I'm no expert, but I've always heard that 10W30 is better hot. both 5W-30 and 10W-30 have essentially the same VISCOSITY hot, but the 5W-30 requires more viscosity improves to achieve that same viscosity since you are starting with a lighter weight oil. Therefore, 5W30 has less base oil and more viscosity improvers to compensate for the lighter base oil. Oil is what protects the engine, not the viscosity improvers, which is why 10W-30 is better hot. Same thickness, but a bit more oil and less additives so it doesn't beak down as much and provides better lubrication. 'Course, most wear occurs at startup, which is why 5W-30 is better in cold weather. Unless it's really cold (below freezing) their really isn't that much difference either way. I use 5W-30 in the winter, 10W-30 in the summer just cause it gets so hot hear in Texas. Modern oils are so good though, that the difference is probably minimal at best unless you do any racing which gets the oil REALLY hot, normal driving either is just fine, can't really go wrong either way, though I would use 5W-30 in cold climates in the winter just to be safe. Although a friend of mine ran Penzoil 10W-30 year round in central Illinois in his Citation X-11, got over 200K miles out of that engine, was his only transportation year round and he ran the hell out of the car including heavy autocrossing. Again, either oil will work just fine :) I do think alot of the reason automakers recommend the lighter oils though is for cold start emissions and gas mileage more than anything.

UFOVette

I would stay with 5W30. Since 5W30 Mobile one will not start to break down until over 400 degree oil temps, which you will not see unless your cooling system fails.

1990bevile

change your oil a little more frequently and dont even worry about 10w30. Go 5w30

Viprklr

fxrhm

GM recommends either - I say in hot climates like here in Phoenix, use 10-30, which I do.

quietgirl

0w30 here.