TGMO 0W-20 SN, TBN/TAN, 5170 M, 85 Corolla 4A-LC

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This is my second UOA with Toyota (TGMO) 0W-20 SN/GF-5 made in US by ExxonMobil.

The OCI duration is 5170 miles, 335 days. No makeup oil was added and the oil consumption was minimal -- about 0.3 - 0.4 quarts over the OCI and probably mostly due to a small leak at the oil pan. Almost no oil consumption is thanks to replacing my valve-stem oil seals. Oil-change capacity is 3.5 quarts with oil-filter change. Dry-fill capacity is 3.9 quarts. The filter used is Toyota 90915-YZZF2. Cumulative miles and age on the 1.6-liter carbureted SOHC engine at the time of the UOA sample is 254205 miles, ~ 29 years. In addition to high-speed freeway driving, the car saw a lot of short trips that you would think would be hard on the oil. Temperatures in the area were mild, warm, or hot during last year.

I used the $30 (shipping included) high-quality aluminum Blackstone vacuum pump for oil sampling and it worked wonderfully. It's clean, fast, accurate, and lets you have a UOA oil before you change the oil so that you can use a different oil next time if you aren't satisfied. I strongly recommend it to everyone over the messy drain-hole method -- it's much, much, much better. Note that the pump doesn't touch the oil and doesn't require cleaning.

My UOA results, which are 2.5/2.6/12/3.9/2.6 for Al/Cr/Fe/Cu/Pb seem very similar to the universal averages for this engine, which are 4/2/14/5/3 according to Blackstone. So, in that sense the 0W-20 isn't doing much different than the 10W-30 or 10W-40/15W-40 people typically run with this engine. However, I would like the iron, chromium, and lead numbers to come down a little.

Note that the TBN and TAN are 5.25 and 3.33, which are both very impressive. My rule of thumb is that the TBN needs to stay larger than the TAN over the OCI for optimal protection. I saw that in many engines TAN will quickly exceed TBN. I don't have that problem and the TGMO would probably be good for up to about 10,000 with this engine. One more note: Blackstone uses an outdated test for TBN and their TBN number are underestimated. This TBN value by WearCheck is the true TBN using the modern test method.

My question: Should I use TGMO 0W-20 SN for the next OCI or perhaps switch to a thicker oil such as Mobil 1 0W-40 SN? Note that in the past I used a 15W-40 for many years but I don't have any UOA on that. I had used PYB 5W-20 SN for one OCI after the long 15W-40 spell and PYB 5W-20 SN UOA was significantly worse in terms of wear than the TGMO 0W-20 SN. However, this could be because 15W-40 HDEO intended for heavy-duty diesel engines was causing high wear in my gasoline engine and I was seeing some leftover wear metals. So, what do you guys think? Would a thicker oil like Mobil 1 0W-40 SN make things better or worse?

These are my previous UOAs, TGMO 0W-20 SN @ 249035 miles and PYB 5W-20 SN @ 243729 miles:

Previous Blackstone UOAs

After all this is said, here comes the new UOA. Note that they didn't have a reference VOA for accurate determination of oxidization, nitration, sulfation, glycol coolant, etc. through the IR spectroscopy. However, there could be some small coolant intake through the head gasket because sodium seems a little high.

wc_2014_02_22_1.jpg


wc_2014_02_22_2.jpg
 
Originally Posted By: Gokhan
Would a thicker oil like Mobil 1 0W-40 SN make things better or worse?

No idea, but I'd try it anyway, just to see what effect it would have, if any.
smile.gif


Thanks for the report.
 
Note that they have a large concentration of ~ 100 ppm (apparently) trinuclear moly in the TGMO 0W-20 SN, which is quite strong. Viscosity at 8.68 cSt is nice and strong for an xW-20, not much lower than an xW-30 (9.3 cSt minimum for fresh oil), with no evidence of shear. Many conventional and even fully synthetic 5W-30s shear to a similar viscosity. However, some might caution that there might be thickening due to some coolant contamination. Regardless, TGMO 0W-20 SN is looking great overall.
 
Originally Posted By: Quattro Pete
Originally Posted By: Gokhan
Would a thicker oil like Mobil 1 0W-40 SN make things better or worse?

No idea, but I'd try it anyway, just to see what effect it would have, if any.
smile.gif


Thanks for the report.

My feeling is that it won't do better and the small high-mileage engine will be more sluggish with rougher idle because of the higher viscous-drag force, of course with a decrease in fuel economy as well. However, it could be good just for the sake of an educative experiment.
 
Thanks for the UOA Gokhan! The Silicon level seems slightly elevated, but Mobil tends to utilize roughly half the measured amount (5-6 PPM) as an anti-foaming agent which would account for the increased levels. I definitely understand the desire for the Iron, Chromium, and Lead to come down, but with your UOA being slightly lower than the universal averages, plus the 250K miles on the motor; I wouldn't worry too heavily about it unless you note higher particle wear down the road. Other than that, your report was well thought out and to the point!

As far as the 0W40 goes, I'd definitely give it a run. You'll get roughly 25% higher levels of ZDDP (which may decrease wear), may decrease oil consumption (even though yours is low to begin with) and keep compression higher, easy pump-ability, and shouldn't have an issue with the thicker 40 grade (my brother has an early 90's Camry with similar mileage and uses 20W50 to slow oil leak/consumption and hasn't reported any sluggishness or cold starting difficulties in SoCal).
 
Originally Posted By: Analyzer
As far as the 0W40 goes, I'd definitely give it a run. You'll get roughly 25% higher levels of ZDDP (which may decrease wear), may decrease oil consumption (even though yours is low to begin with) and keep compression higher, easy pump-ability, and shouldn't have an issue with the thicker 40 grade (my brother has an early 90's Camry with similar mileage and uses 20W50 to slow oil leak/consumption and hasn't reported any sluggishness or cold starting difficulties in SoCal).

Great report and care effort is paying well for you Gokhan!
Although instead of the 0w-40 you could very well use a 15w-40 and go for a UOA at 4k or 5k miles, before changing oil in next run! This because above reference to 20w-50 in camry not giving sluggishness seems in line with what i would expect from your very "nicely broken-in & well-maintained" older model 1985 Toyota Corolla as well, with not much expectation of sluggishness as it is not a modern toyota engine anyways...
 
As I mentioned, I ran 15W-40 in this car for many years and it's too thick with its HTHSV = 4.3 cP. With 15W-40, idle is rough and horsepower drops. When you have a 74 HP engine pulling a 2500 lb car, every horsepower counts. 15W-40 has way too much viscous drag (thanks to 4.3 cP HTHSV) and doesn't have the friction modifiers of the GF-5 oils either. People use 15W-40 in old cars to control oil burn but my engine doesn't burn any oil at all to begin with.

This engine didn't run as smooth with any oil as it has with the TGMO 0W-20 SN.

It could still be an interesting experiment to try M1 0W-40 SN. I don't like it that it has too much detergents and not as much friction modifiers as TGMO 0W-20 SN. It probably has some ester Group V instead of AN Group V, which I don't like either. Thick oil may also starve the valve stems and piston rings and more ZDDP could be just more poison to the catalyst. However, again, it could be a good experiment to see if the wear improves or get worse. I wouldn't be surprised if it got worse.
 
Regarding high sodium, it might be caused by some of the coolant overflown from the coolant overflow reservoir sucked into the engine by the cold-air-intake hose right below it. I like to top off the reservoir and let the excess overflow when the engine gets hot but I won't do this in the future and see if it makes a difference in the sodium in the next UOA. There is a leaky water-outlet gasket that I need to replace and I have been adding coolant occasionally. I don't see any white smoke from the exhaust; so, I doubt it's being sucked into the combustion chamber.
 
Anyone know where to find the virgin values of sulfation, nitration and oxidation? Those numbers look high.
 
Originally Posted By: badtlc
Anyone know where to find the virgin values of sulfation, nitration and oxidation? Those numbers look high.

Actually, there is no such thing as sulfation, nitration, and oxidation for virgin oil. They are all measured for used oil taking virgin oil as reference.

Disregard the sulfation, nitration, and oxidation numbers in my UOA, as they are meaningless. They are determined by infrared spectroscopy, which they did for me, but they need the virgin oil as a reference to subtract from the spectrum. However, they didn't have the TGMO 0W-20 SN in their virgin-oil database; so, they had no reference oil for me. Therefore, the numbers they put for sulfation, nitration, and oxidation are just some default values that come up automatically in their software, not actual measured values.

Perhaps at one point, I will send them a sample of virgin TGMO 0W-20 SN so that I could get actual values of sulfation, nitration, and oxidation in the future.

However, as you see, the TAN is fairly small. Since sulfation, nitration, and oxidation all produce acids and cause the TAN to increase, this impliues that sulfation, nitration, and oxidation are all fairly small as well.

So, from the TBN and TAN, Toyota is indeed right that TGMO 0W-20 SN is a 10,000-mile-OCI oil for Toyotas. Even with my 85 Corolla, it looks like the oil could easily be healthy for a 10,000-mile OCI. (I use TBN > TAN as the criterion for healthy oil.)
 
Ah, I see.

Just to clarify, I understand they didn't provide them for your report and that answers my question, but.......sulfation, nitration and oxidation numbers do exist for virgin samples. They should be very low to non-existant unless there is ester. Ester based oils will likely have an oxidation level even in virgin form.
 
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Three thoughts:

Nice report, thanks.

They don't make 'em like they used to, and

The 0w40 sounds like a great idea for an experiment.
 
Originally Posted By: Kuato
Three thoughts:

Nice report, thanks.

They don't make 'em like they used to, and

The 0w40 sounds like a great idea for an experiment.

Thank you Kuato.

I actually decided to stick with TGMO 0W-20 SN. Engine has been running better and smoother with TGMO 0W-20 SN than with any other oil. My wear metals have been decreasing with every TGMO 0W-20 SN OCI. If there is actually a coolant contamination as inferred from the high sodium, the performance of the TGMO 0W-20 SN is even more impressive. The viscosity seems fine for this engine, despite the 1985 owner's manual recommending between 10W-30 and 20W-50 and not even recommending 5W-30 except in cold winter. I see no reason to switch to a thicker grade -- don't fix something that isn't broken, especially if it's working well.

It could have been an interesting experiment, but then this is my own car and not a test car and I want to use the best oil in it, not the obsolete xW-40 grades not specifically tuned for gasoline engines only the European car makers use today.
smile.gif
 
Hi,
Peter Gokhan - Many engine Manufacturers recommend to OC when the TBN is around 33% to 50% (depending on engine family) of the virgin TBN

In extending OCIs I used Fe and Soot (diesels) max. as the prime limiting factors and at OCI the TBN average was around 50%. OCIs averaged 90k kms
 
I had them run an FTIR (Fourier-transform infrared spectroscopy) on the virgin-oil sample I sent later so that I could get a baseline for the sulfation, nitration, and oxidation values, which directly correlate with the TAN and oil life. Of course, virgin oil has no sulfation, nitration, and oxidation but the numbers that are calculated by a self-consistent algorithm are to be subtracted as a baseline from the UOA samples.

The new UOA results below have the virgin-oil baseline values for the sulfation, nitration, and oxidation subtracted from the UOA values, and therefore, the UOA values are now normalized.

UOA values normalized by subtracting the virgin-oil baseline values:

Sulfation: 36%
Nitration: 67%
Oxidation: 32%

Nitration is on the high side for some reason. Perhaps ignition timing was advanced too much.

"FTIRs work by an auto-reference algorithm and the results are strictly an estimate of what the FTIR program calculates for the values. With the older FTIRs, you had to have a baseline of the actual product and process the used oil sample against it to establish true values. This is typically not done by used oil analysis production laboratories as it would require a baseline reading of each individual new oil product requiring the lab to know what the exact product was before processing. Very impractical, and clients often do not report the specific product anyway so you are still left with an estimate. What I did with your samples was to use the new unused values of the new oil as the baseline and subtracted them from the readings of the used oil. I did not adjust any of the new oil values."

UOA_TGMO_0W-20_SN_2014-02-22.jpg
 
Originally Posted By: yvon_la
that isn't a virgin oil analysis,isnt this a used oil analysis?

It's UOA after the FTIR sulfation, nitration, and oxidation values normalized by subtracting the VOA baseline values as explained above.
 
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