2006 Cobalt, Castrol GTX 5W30

[PF52]

Yay, my first ever oil analysis. Feel free to comment since most of this stuff I have no idea what it is. TBN for example; what is that?

Car: 2006 Chevy Cobalt, 43,555 miles, 2.4 liter engine.
Oil: Castrol GTX, 5W30, 5000 miles on oil with none added.

Charles: Nothing unusual showed up in the initial sample from your Cobalt. Wear generally read at or below averages and the metals are properly balanced. Universal averages show normal wear after about 5,200 miles on the oil. The viscosity was a little low, reading more like a 5W/20, but the flashpoint was normal so the viscosity wasn't due to any contaminants and isn't a big concern. The TBN read 2.0, so the oil has active additive left, but not a whole lot. 1.0 is considered too low. All in all, things look good here at 43,555 total miles. Sodium is from additive in the oil itself.

Aluminum 4
Chromium 1
Iron 8
Copper 1
Lead 0
Tin 0
Molybdenum 7
Nickel 0
Manganese 0
Silver 0
Titanium 0
Potassium 2
Boron 2
Silicon 5
Sodium 153
Calcium 2457
Magnesium 8
Phosphorus 682
Zinc 798
Barium 0

SUS Viscosity @ 210F 55.7
cSt Viscosity @ 100C 8.99
Flashpoint in F 370
Fuel% 0
Antifreeze% 0
Water% 0
Insolubles% 0.3
TBN 2.0

 

[Cutehumor]

what was left on the OLM? sodium is probably castrol add pack

 

[Bill in Utah]

Looks good. Love those Ecotec motors.

I'd be happy with the UOA. TBN is how much of the amount of active additive left in the oil.

What type of driving do you do and how long was this OCI?

Take care, Bill

 

[Patman]

The sodium is definitely in the additive pack, it appears Castrol is adding it to their 5w30 GTX now too (originally it was just in their 5w20)

I'd be tempted to go with GTX 5w20 in here and see how it performs, since GTX 5w20 typically will stick right around 9cst at 100c anyhow, but yet you'll get the added benefit of it being a little bit thinner on startup too. And if you do short trips with this vehicle at all the 5w20 might just show even lower engine wear (not that there is anything wrong here, the numbers are very good!)

 

[PF52]

Thanks for the replies guys! To answer your questions, the OCI on this car has been every 5000 since new, which translates to just below 50% on the OLM (It takes about 9500 miles for it to reach 0%). I do a lot of short trips during the week but they are offset by long drives on the interstate on every couple weekends, many of several hundred miles or so. Pure One filter too by the way.

 

[ChiTDI]

BITOG's home page has an explanation of TBN and "how to read UOAs". Fascinating stuff for the nonchemist. Like me.
Your report looks good to me.

 

[jorton]

I believe "active additive" is the anti-oxidant. Phosphorus and zinc(zddp). It neutralizes acids that form sludge. After it gets tired out, sludge fighting job is passed on to detergents.

Oil report looks great!

 

[zulu]

Wear metals look really good, but the TBN bugs me. How can it be down to 2.0 and the OLM still indicates 50% life left? That just makes no sense, especially since I'm trying to build up the courage to trust my own OLM.

 

[Turk]

The OLM does not monitor the condition of the oil.

 

[Bill in Utah]

Originally Posted By: zulu
Wear metals look really good, but the TBN bugs me. How can it be down to 2.0 and the OLM still indicates 50% life left? That just makes no sense, especially since I'm trying to build up the courage to trust my own OLM.


And it may stay at 2.0 for the next 2k miles then drop. It may drop slowly.

For your type of driving the OLM may drop quickly. Its hard to say. But the UOA shows you have a excellent wearing engine.

Why don't you go to 25% left and change the oil and see where you are at?

I'd bet it will be good.

Take care, bill

 

[FZ1]

Looks like it's a 5k oil in your application. I'd stay with 5k oci's.

 

[PF52]

Originally Posted By: FZ1
Looks like it's a 5k oil in your application. I'd stay with 5k oci's.


I'll probably do just that and get another analysis a couple changes down the road; they just sent me two more sample containers.

Had I added any oil between changes, the TBN might have looked a little better, but not leaking/burning any oil, I didn't need to add anything, so there's been no "refreshing" of additives.