GC 0W-30 | '10 Impreza | 4.2-5.7k mi

[Scotthew]

I've been using 0W-30 GC since I bought my car 34k mi ago. Unfortunately, I've only been bothering with UOAs for the last year or so. For the most part I've been quite happy with GC, but the most recent test showed a suspiciously high particle count on both the used and virgin samples and the TBN fell to 4.2 after 5700 miles.

http://i.imgur.com/EoH0L3k.png?1

 

[Quattro Pete]

Here you go:

 

[Scotthew]

You're a wizard, Pete.

Thanks!

 

[Quattro Pete]

Report looks fine to me. I don't think I've ever seen Silicon level of "0" on a UOA. You have suspiciously large number of zeros on this UOA...


Quote:
but the most recent test showed a suspiciously high particle count on both the used and virgin samples and the TBN fell to 4.2 after 5700 miles.

Particle count? What specifically are you referring to?

TBN of 4.2 after 5700 miles is pretty normal, IMO.

 

[Scotthew]

Originally Posted By: Quattro Pete
Report looks fine to me. I don't think I've ever seen Silicon level of "0" on a UOA. You have suspiciously large number of zeros on this UOA...

I was thinking that too. And since the additive package is a bit lower on that sample as well, I suspect the ICP was a bit off on calibration. Perhaps I'll need to rerun the sample.


Originally Posted By: Quattro Pete
Particle count? What specifically are you referring to?

It's under the "Oil Cleanliness" section. Oddly enough the virgin oil had a higher particle count that my used oil. Though I've heard that the additives can cluster and give false readings on the particle counter. Something to keep an eye on in my future samples. Does anyone else have particle count data for GC?

Originally Posted By: Quattro Pete
TBN of 4.2 after 5700 miles is pretty normal, IMO.

I've seen diesel samples with over 500 hours and TBNs still above 10. Granted that's a bit of apples and oranges. But still, I was hoping I could extend the life to 6000 mi, but now I'm thinking I should stick to around 4.5-5k

 

[Quattro Pete]

Originally Posted By: Scotthew
But still, I was hoping I could extend the life to 6000 mi, but now I'm thinking I should stick to around 4.5-5k

TBN of 4.2 means there is still plenty of additive left. You can easily do 6K miles.

To get the full picture, you also want TAN. When TAN starts exceeding TBN, it's time to change your oil.

 

[Scotthew]

Originally Posted By: Quattro Pete
TBN of 4.2 means there is still plenty of additive left. You can easily do 6K miles.

To get the full picture, you also want TAN. When TAN starts exceeding TBN, it's time to change your oil.

Very true. As I wasn't paying for this sample, I didn't want to use one of the TAN titration kits, and the spectroscopy method requires a baseline to compare against and I couldn't find a good match in our list.

Does anyone have TAN data for GC?

 

[Apollo14]

You could go by the 50% to 65% of virgin TBN "rule".

 

[JimPghPA]

I ran GC for 8K miles over 24 months in our 2001 Impala with the 3.4 liter engine, and the TBN was 2

Our current fill of GC has been in the engine for 18 months and has 7500 miles on it. I am waiting until the milage is 8K then I am going to change it.

BTW, I use an extra large (long) Purolator oil filter that also gets changed at every oil change.

 

[Garak]

Originally Posted By: Quattro Pete
Report looks fine to me. I don't think I've ever seen Silicon level of "0" on a UOA. You have suspiciously large number of zeros on this UOA...

Yes, I'd be asking them for a retest or to explain their methodology. Is anything they consider normal automatically reverted to zero or something?