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 One more note: Blackstone uses an outdated test for TBN and their TBN number are underestimated.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.
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.