Magnatec 5w30 - 9.5k mi [2007 Cobalt - 125k mi]

[John_Dude]

0.5 quarts of make-up oil added through this OCI, also castrol magnatec 5w30. This is the full synthetic version. Last time I added 1 quart of make-up oil, close to the end of the OCI (within last 1.5k miles probably). Filter was an ACDelco PF457G (the older hengst version), last time was wix xp. Oil life monitor indicated 10% left. Driven 90% on the freeway, 14 mile commute each way. TBN is too low for me, I would like to keep it above 2. I'll just run 9k mi at the most from now on. Pretty satisfied with a $25 oil change. The viscosity held up very well again.

 

[Danno]

Good reported but pushed the oil change a little too deep evidenced by the low TBN number. Try 7000 - 8000 miles next time.

 

[deven]

Originally Posted By: Danno

Good reported but pushed the oil change a little too deep evidenced by the low TBN number. Try 7000 - 8000 miles next time.

I disagree. The viscosity is within range, the wear metals are low and TBN is not below 1.0 which is when the oil is depleted. I would personally stay at 10,000 mile OCI with this oil. Its the sweet spot for it.

 

[vinu_neuro]

Originally Posted By: deven

Originally Posted By: Danno

Good reported but pushed the oil change a little too deep evidenced by the low TBN number. Try 7000 - 8000 miles next time.

I disagree. The viscosity is within range, the wear metals are low and TBN is not below 1.0 which is when the oil is depleted. I would personally stay at 10,000 mile OCI with this oil. Its the sweet spot for it.

TBN can be above 1.0 with elevated TAN. It's why TAN is also needed and why TBN retention isn't the be all and end all.

 

[John_Dude]

I read that blackstone kinda pulled the 1.0 minimum tbn out of their [censored]. Oil manufacturers generally look for tbn to fall to either 1/3 or 1/2 of the voa amount when it's depleted. Dont have a tan option with wix so I'll consider 2 my baseline. I figure that the oil becomes acidified from blow by, which if excessive would cause oil consumption. With half a quart over 9.5k mil the rings are probably pretty tight still. I'm impressed that the magnatec has slowed my oil consumption. I used to see 1 quart consumption over 5-6k mi, this was my 2nd run with magnatec. I wonder if the pao or esters are swelling the seals, although the oil pan has been dry the whole time. Could be the valve stem seals.

 

[John_Dude]

This was actually the older synthetic blend version of magnatec.

 

[deven]

Originally Posted By: vinu_neuro

Originally Posted By: deven

Originally Posted By: Danno

Good reported but pushed the oil change a little too deep evidenced by the low TBN number. Try 7000 - 8000 miles next time.

I disagree. The viscosity is within range, the wear metals are low and TBN is not below 1.0 which is when the oil is depleted. I would personally stay at 10,000 mile OCI with this oil. Its the sweet spot for it.

TBN can be above 1.0 with elevated TAN. It's why TAN is also needed and why TBN retention isn't the be all and end all.

If the TAN was elevated you'd most likely see more skewed numbers and the viscosity would suffer along with elevated copper and tin numbers as well. This was told to me by a well known gentleman who used to decipher UOA's for a living and was a member here a long time ago.