Toyota TGMO 0W-20 SN VOA with VI, TBN, and TAN

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Originally Posted By: Gokhan
TGMO 0W-20 SN WearCheck Laboratories baseline values for virgin oil:

Sulfation: 58%
Nitration: 33%
Oxidation: 68%


So with your VOA BN, AN and oxidation figured out, what does that tell you about your future OCIs with the Corolla?
 
Originally Posted By: Blue_Angel
Originally Posted By: Gokhan
TGMO 0W-20 SN WearCheck Laboratories baseline values for virgin oil:

Sulfation: 58%
Nitration: 33%
Oxidation: 68%

So with your VOA BN, AN and oxidation figured out, what does that tell you about your future OCIs with the Corolla?

After 5,170 miles, TBN minus TAN was 1.92, which is very good, and oxidation was only 32%. I think it could easily do 10,000 miles / 1 year, which is the OCI specified in the 1985 owner's manual for API SF or SF/CC conventional oil in normal driving conditions. I don't need to drive to work; so, I can only put about 5,000 - 6,000 miles a year; therefore, I change the oil once a year. It's good the freshen up the oil every year even if the oil condition is still good, as there is nothing more important for the longevity of the engine.
 
Originally Posted By: Shannow
Take a 2" journal, 0.0015" radial clearance, and 6,500RPM, and assume that the journal is really pushed hard on the loaded side, and away from the feed hole.

The shear rate adjacent to the feed hole is 750,000, 75% of the 1,000,000 that HTHS is measured at.


So if the shear rate on the wide gap side of the bearing in that scenario is 750,000, what is the shear rate at the wedge side of the bearing?

Also, is it possible to determine what the theoretical "average" shear rate is for all the oil in the bearing?

Assuming the same clearance-to-diameter ratio for a turbocharger bearing (maybe it's a larger clearance ratio?), what would the shear rate be for a 1/4" journal spinning at 200,000 RPM?
 
The shear rate through the minimum clearnace is the appropriate shear rate for the "lubrication" part of the hydrodynamics.

Using the overall bearing clearance for the open side is OK, because the thin part of the wedge is so small relative to clearance,the errors are very low in assuming that the overall clearance is the gap.

To do the thin side, you have to get into the bearing characteristics, sommerfeld numbers, and the full on calculations to determine how many um the "wedge" is, as a um here and there is 10-20% error.

My calculation of the shear rate around the oil hole was to see if the bearing was in high shear the whole of the way round, and it seems pretty close...you don't need to know the average.
 
Originally Posted By: Gokhan
Originally Posted By: Gokhan
TGMO 0W-20 SN WearCheck Laboratories baseline values for virgin oil:

Sulfation: 58%
Nitration: 33%
Oxidation: 68%

After 5,170 miles, TBN minus TAN was 1.92, which is very good, and oxidation was only 32%. I think it could easily do 10,000 miles / 1 year, which is the OCI specified in the 1985 owner's manual for API SF or SF/CC conventional oil in normal driving conditions. I don't need to drive to work; so, I can only put about 5,000 - 6,000 miles a year; therefore, I change the oil once a year. It's good the freshen up the oil every year even if the oil condition is still good, as there is nothing more important for the longevity of the engine.

Hi Gokhan! So you will not go for it (10,000 miles) then... by the way why do you say 10k miles / 1 year OCI, is the TGMO 0w-20 not suitable for lasting longer than 1 year ?
 
Please excuse the necro-bump.

What's with the sulfur number here? I don't browse UOAs and VOAs a heck of a lot, but 3543 ppm strikes me as... very large.
 
Originally Posted By: d00df00d
Please excuse the necro-bump.

What's with the sulfur number here? I don't browse UOAs and VOAs a heck of a lot, but 3543 ppm strikes me as... very large.

That's 0.35%. Limit on Group III is 0.03%. So, it's coming from the additives. ZDDP and moly both have sulfur. In fact, trinuclear moly is mostly sulfur. Someone who knows the molecular formulas of these can easily calculate how much sulfur is coming from them given the Zn and Mo numbers and then see if there is still any balance left over from other additives.
 
I just did a UOA on my highlander with the same batch of Toyota oil. Moly was only 38.
Same label and code on back. I did buy the case a couple of months ago.
 
It's reasonable to believe the dispersement of additives at the blending place is not always consistent. I suppose they do run into shortages and lessen amounts of a specific additive, on occasion.... I reckon anyways!

Could also mean the holding tank for moly was running low and dispersing less..... until refilled. Could have been a small clog in the line...... many reasons on why your moly level is different. Overages and shortages of specific ingredients happen in everything of multiple blends..... in every industry.
 
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