2015 Tacoma 4.0 V6, 9.8K mi. Amsoil Signature 5W30

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The following is the latest UOA on my 2015 Toyota Tacoma 4.0 V6. This oil was in use for 7.5 months, almost 10,000 miles. This nearly doubled my last UOA interval, and is double what the manufacturer recommends. Some interesting things in this UOA. First, some things that were flagged, but not surprising: Copper is still high, but is trending down. I believe the copper is coming from the engine oil cooler, which this engine has as a part of the towing package. Also, Silicon is still high, but still trending down on a per-mile basis. I have seen this on many Toyotas that I have bought new, like this one, and I believe it is coming from the sealers Toyota uses in the engine. Some other notable things: I was rather surprised that the viscosity was slightly high - virgin VOA is about 10.5. Also slightly surprised that insoluables went from 0.1 to 0.3. The oil filter used was a Mobil 1 M1-209. TBN and TAN look pretty reasonable to me. I think Iron overall, although normal, is higher than what I typically see on most Toyota engines...I suspect the engine is not 100% broken in yet, I may have jumped the gun on going to a 10K miles UOA interval. Blackstone commented that "perhaps the oil got hot" - We did not tow anything during this interval, the heaviest load consisted of 4 passengers on a highway trip. During this interval, the truck was used for about 35% highway driving, 65% city/suburban driving. Comments? My plan is to do another 10K miles interval. The oil was changed and Amsoil signature 5W-30 was used again for the new interval.
 
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As a owner of a 06 4.0l Tacoma this is about as good as it will get don't expect much improvement. Air box sucks never seems to seal corectly but engine will run long time looks good.
 
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Do TAN and TBN have predicted relationship? What I means is if we have only TBN or TAN number, can we determine the other number with acceptable accuracy? Also what is acceptable TAN number ?
 
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I'm not sure the cost per quart on the Amsoil SS but I'd think that there are other oils that would produce similar results at a significantly lower cost for the same mileage run. Other than that I wouldn't say that there's anything to worry about here and your 4.0 is breaking in nicely.
 
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You overrun the oil. And you see clearest confirmations/ First:
Originally Posted By: btanchors
Some other notable things: I was rather surprised that the viscosity was slightly high - virgin VOA is about 10.5.
Second:
Originally Posted By: btanchors
TBN and TAN look pretty reasonable to me.
But the conclusion is not correct: TBN, being twice lower than TAN, gave you direct signal that you should not go that long. The rule of thumb is TBN >= TAN.
 

btanchors

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timeau: I'm inclined to agree with you that the increase in viscosity is a sign the oil is at or approaching its limits. But I am less inclined to agree regarding the TAN/TBN. This oil starts with a Virgin TAN of about 4.6. Because of that, I am not convinced that the rule of thumb of TBN >= to TAN applies. For oils with a high starting TAN, I think it may be more valid to compare the delta in TAN (from Virgin Level). In other words, TBN should be >= delta TAN. In this example, that gives us 2.9 >= (5.8 - 4.6) or 1.2. There are other oils I have seen with a Virgin TAN of over 5. Do you really believe that those oils should be changed out when the TBN reaches 5? That doesn't make sense to me. I would be interested in hearing someone authoritative chime in (Molecule?) on this, as I have had this question for awhile.
 
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#'s are great IMO. You didn't jump the gun on the 10k OCI. Keep doing what you're doing - likely the FE will come down from what is already an acceptable level for a new engine. Just keep it topped off during the 10k runs. Lay a little grease around the air filter seal.
 
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