Just A Dumb Oil Question

[RVJ]

This is not a voice your opinion on when I should change the oil, it is a why is it happening question.

When I had my 09 Sierra with the iron block 5.3 I was changing the oil at around 3,000 miles. I used Valvoline and it still looked pretty clean when I dropped it. When I bought the 2010 Sierra with the Aluminum block 5.3 I changed the oil at 1000 miles and put Castrol GTX in it, mainly because It was a tad cheaper and I felt it was a good oil anyway. Yesterday, I checked the oil since it has about 2,000 miles on it to see where it measured on the dipstick and I was shocked. The oil although on the full mark, was blacker than I have ever seen oil get.

I'm wondering if the change from iron block to aluminum block would be the diference or the change from Valvoline to Castrol GTX might be the deciding factor. Anyone have a thought on the matter?

I drive the same distance and the same route every day, buy the same gas at the same station every week, and always drive like an old man all the time. My driving rarely changes at all.

[ChevyTech77]

Any differences in seasons? Colder temps mean engine running a richer fuel mixture longer and the same drive time doesn't get everything "burned off" as much as in the summer.

 

Castrol is also a slightly darker oil out of the bottle than Valvoline is, in my experiances. Both great oils and I'd say that you don't have much to worry about.

[RVJ]

Any differences in seasons? Colder temps mean engine running a richer fuel mixture longer and the same drive time doesn't get everything "burned off" as much as in the summer.

 

Castrol is also a slightly darker oil out of the bottle than Valvoline is, in my experiances. Both great oils and I'd say that you don't have much to worry about.

 

I did notice the Castrol was darker for sure. I drive 16 miles each way to work and back 5 days a week. I never thought about the colder weather effecting the oil. I'm thinking going back to Valvoline and staying with it. I'm averaging about 16.6 mpg and the truck does get up to operating temp. each trip I'm assuming.

[Spurshot]

As you well know, each engine is unique in some way, even within the same product line. No two are identical. You're latest engine could have some blowby issues at this stage in it's life. This may or may not get better with more use. Certainly we've all seen new engines with problems, some of which correct themselves.

 

A leakdown compression check may give a clue.

[RVJ]

Would blow by darken the oil prematurely?

[txab]

Would blow by darken the oil prematurely?

Yes it can.

 

Just put some miles on your engine. Use whatever oil you wish. I see that you have nothing to worry about at this point.

[RVJ]

Ok, thanks.

[Wingnut]

If you're really worried, it's pretty cheap to send oil off for testing.

[RVJ]

I,m not really worried, more curious than anything. Truck runs and sounds excellent. Just wondering if Castrol cleaned better than Valvoline or if aluminum block created more deposits than iron block. Either way, I have no issues with the truck.

[Black02Silverado]

Two different engines, two different oil chemistry. The fact that the oil is darker can take on so many different meanings. For one it is keeping your engine clean by keeping the contaminants suspended in the oil which is what you want.

 

I don't think there is an issue.

 

Now when direct injection starts to become the norm there is going to be some issues. We are seeing it now with some of the DI engines in the Acadia, Onclave, Travers models. The oil is getting fuel diluted and that isn't good.

[RVJ]

Ok, thanks for the comments. I'll just make sure it's full and changed and I'm sure I'll be ok.