Pennzoil (PYB) 5W-20 SN, 5,432 M, 85 Corolla 4A-LC

[Gokhan]

I just got this UOA results. Pennzoil yellow bottle conventional 5W-20 SN/GF-5, 5,432 miles / 7.4 months on the oil, 243,729 miles on the 85 Toyota Corolla 4A-LC engine (AE82, not AE86). OEM oil filter (90915-YZZF2) and air filter and pretty much OEM everything.

Engine doesn't use any oil, except I lost about a half quart during the OCI mostly due to a small leak at the oil-pan seal. No makeup oil was added.

Wear numbers are not too good, although not too bad looking at the universal averages, which are for less than half the OCI I went for.

TBN was down to 2.0, not too bad but signaling the end of life for the oil.

Previous oil was Mobil Delvac 1300 Super 15W-40 CJ-4/SM.

The new fill is Toyota Genuine Motor Oil 0W-20 SN/GF-5 (made in USA by ExxonMobil). I got if for $5.50 a quart at my local dealer, after some good negotiation. It seems to be a pure Group IV / Group V oil (no Group III) from its nauseating odor. In contrast Mobil 1 0W-20 has a much milder odor of the same kind, probably indicating less Group IV or V and more Group III in it.

Now the question is are the wear metals because of switching to a lighter grade or is it leftover from the previous oil? Or did the thinner oil clean up the sludge and varnish of the thick HDEO so well that the stuff I am seeing came from the old deposits?

By the way, I am very pleased with the Toyota 0W-20: Engine runs very smoothly and I see a noticeable decrease in friction and increase in engine horsepower in comparison to Pennzoil yellow bottle 5W-20. I really didn't like the PYB 5W-20. It felt like it resulted in too much friction and the oil degraded quickly. Synthetics do make a difference, at least in fuel economy and horsepower.

I will go with the Toyota 0W-20 with this OCI, considering how great the engine runs with it. Probably never switching back to dino oil again in the future, given how much better the engine runs with the synthetic.

Should I worry about the viscosity being too thin and consider switching to Mobil 1 0W-40 SN? Note that PYB end of life viscosity was not much lower than that of a 5W-30 (9.30 cSt minimum), probably due to some mix of the 15W-40 from the previous OCI.

I had also a VOA with this oil. Here it is for comparison. I wonder where the boron went. Note that the additives are higher in the UOA because of the leftover from the previous oil (Delvac 15W-40 HDEO).

Comments are welcome; so, please discuss.

 

[DemoFly]

Why are you running 20 weight?

 

[dave1251]

PYB held up very well in this engine that is nearly 30 years old. Your Toyota 0W-20 should be fine. I understand your chrome worries but it is not too much out of line. I would use your current fill of Toyota 0W-20 should be fine. If your chrome PPM are still high after the next sample I would advise to step up your oil grade. Keep in mind the engine age and miles, the car has served its glory days many moons ago and it may go another 27 years and 250K or it could be done next week.

 

[Turk]

So, you're going from a 15w-40 to 5w-20?

"some mix of the 15W-40 from the previous OCI"

That's A LOT of leftover additives... BUT the viscosity is not much higher though.

 

[pbm]

I would run 5w30 in the winter and 10w30 in summer in an 85' Corolla (especially one with over 200K).
I'm nearly certain that Toyota didn't backspec 5w20 that far back.

 

[Gokhan]

Originally Posted By: tpitcher
So, you're going from a 15w-40 to 5w-20?

"some mix of the 15W-40 from the previous OCI"

That's A LOT of leftover additives... BUT the viscosity is not much higher though.

Good point. So, perhaps, the leftover additives or wear metals are coming from the thinner PCMO cleaning up the deposits left over from the thick HDEO, instead of direct mix with the leftover oil in the engine. The PYB itself would have sheared down to probably around 7.5 cSt.

 

[dave1251]

If this is concern for you add a single quart of 15W40 with your 0W20 each OCI.

 

[Gokhan]

Originally Posted By: dave1251
If this is concern for you add a single quart of 15W40 with your 0W20 each OCI.

I don't expect the Toyota 0W-20 to shear much. I will probably experiment with it for this OCI. Engine seems to be running really well with it. Perhaps if the wear numbers don't get lower, I will switch to Mobil 1 0W-40. OEM recommendation is conventional 10W-30 or thicker, which is equivalent to synthetic 5W-30 thicker, accounting for the shear. I am experimenting with a little bit lower viscosity. There is no oil consumption (having changed the valve-stem oil seals); so, I am good running thinner oil in that department.

 

[ottotheclown]

LOOK at the phosphorus and the zinc # in the voa then look at the results from Blackstone. Where does this increase come from?Then what other # are incorrect??? Yanking my chain comes to mind when you see stuff like this on a regular basis. So best you look at these results with some ya right thoughts IMHO.

 

[Gokhan]

Originally Posted By: ottotheclown
LOOK at the phosphorus and the zinc # in the voa then look at the results from Blackstone. Where does this increase come from?Then what other # are incorrect??? Yanking my chain comes to mind when you see stuff like this on a regular basis. So best you look at these results with some ya right thoughts IMHO.

I wouldn't immediately say that the Blackstone results are incorrect. Chances are that they are correct.

I used Delvac 15W-40 HDEO with this engine for many years and one theory regarding these results is that the thinner PCMO cleaned the heavy deposits left over the years from the thick HDEO, and a lot of stuff came out from these deposits. Again it's only a theory.

Otherwise, according to the Toyota specs, the leftover oil in this engine should only be 0.4 quarts following an oil drain with filter removal.

 

[fdcg27]

Well, for an old design that's done plenty of miles and that was never intended for a twenty grade oil, this UOA looks pretty good.
Viscosity looks fine, while TBN is still within the useable range.
I'd personally use a thirty or forty grade oil in this engine, as most would have done in 1985, especially in a climate like yours, but the old dear appears to have done very well on a multigrade which didn't even exist when it was built.

 

[Gokhan]

Originally Posted By: Gokhan
Originally Posted By: ottotheclown
LOOK at the phosphorus and the zinc # in the voa then look at the results from Blackstone. Where does this increase come from?Then what other # are incorrect??? Yanking my chain comes to mind when you see stuff like this on a regular basis. So best you look at these results with some ya right thoughts IMHO.

I wouldn't immediately say that the Blackstone results are incorrect. Chances are that they are correct.

I used Delvac 15W-40 HDEO with this engine for many years and one theory regarding these results is that the thinner PCMO cleaned the heavy deposits left over the years from the thick HDEO, and a lot of stuff came out from these deposits. Again it's only a theory.

Otherwise, according to the Toyota specs, the leftover oil in this engine should only be 0.4 quarts following an oil drain with filter removal.

I optimistically think that a good fraction of the wear metals are actually coming off the films washed off metal surfaces as a result of switching from HDEO to PCMO, not from actual wear.

HDEOs contain different types of ZDDP (different ratio of primary to secondary) and at higher concentrations and also a different additive package. When protective antiwear films form on metal surfaces, they are in constant equilibrium with the oil in the engine. This film contains P, Zn, Fe, as well as various other metals that come into the oil. It's not inconceivable that when you switch to a different type of oil, a new equilibrium will be established, with the old film washed off and a new film formed. This would explain the high levels of Zn, P, and other metals, including Fe and Cr.

Perhaps the best thing to do is to do 3,000 OCIs on the Toyota 0W-20 SN and watch the UOAs, to see if things normalize after a few OCIs with the 0W-20 synthetic PCMO. I can get the Toyota 0W-20 SN for $5.50 a quart at my local dealer; therefore, it wouldn't be too costly, and it would be a good experiment.

 

[DemoFly]

I would run T6 year round.

 

[Gokhan]

Originally Posted By: DemoFly
I would run T6 year round.

That, or the Mobil 1 0W-40 or Mobil 1 TDT 5W-40 are good choices for the xW-40 viscosity in a gas engine. I would probably prefer the 0W-40.

Compare the Zn concentrations in the UOA and VOA. It's certainly coming off not from the oil itself but as a result of the old antiwear film washed off because of the change from HDEO to PCMO. It could also be because of clearance changes due to viscosity-grade change. This would also explain the high Fe number and possibly even the high Cr number as coming from old antiwear films being washed off and new films being formed.

I won't panic at this point but do UOAs at 3,000 miles OCIs with the Toyota 0W-20 SN synthetic, to see if the Fe and Cr numbers will go down. 0W-20 has fuel-economy and smoother-running-engine benefits over 0W-40.

Another interesting question is that where did all the boron in the virgin oil go? It looks like it might have gone into forming new antiwear films and disappeared from the oil almost completely.

 

[Garak]

Originally Posted By: tpitcher
That's A LOT of leftover additives...


Yes, look at that zinc. That number is what one would expect on a UOA/VOA of Delvac 1300 alone, without any SN/GF-5 PYB diluting it.

Originally Posted By: Gokhan
I used Delvac 15W-40 HDEO with this engine for many years and one theory regarding these results is that the thinner PCMO cleaned the heavy deposits left over the years from the thick HDEO, and a lot of stuff came out from these deposits. Again it's only a theory.


If that's the case, then it flies in the face of the theory that ZDDP in HDEOs isn't as effective as that in PCMOs.

It's not a theory I placed a huge amount of stock in, nor found disconcerting, either.

If Blackstone's zinc numbers are even remotely correct, and the bulk of the oil in the crankcase was SN/GF-5 PYB 5w-20, well, the high zinc levels came from somewhere, and all the ZDDP didn't magically drain out in suspension when you dumped the Delvac.

 

[Gokhan]

I think the high number of Zn is a result of antiwear-film thinning (smaller operational clearance because of change to a thinner viscosity) and/or antiwear-film composition change (change from HDEO to PCMO, with different antiwear additives). A few 3,000-mile-OCI UOAs with 0W-20 should provide more answers, including to the eternal question of the effects of viscosity.

This UOA shows how complicated UOAs are to interpret. There is probably no direct way to judge wear from a single UOA, especially if you switch to a different oil.

 

[ltslimjim]

If he sticks with ONLY one 20 grade of sorts for a while, such a PYB 5w-20 and resamples next time we get a clear picture. Not enough to conclude with considered prior service history.

 

[addyguy]

Originally Posted By: fdcg27
Well, for an old design that's done plenty of miles and that was never intended for a twenty grade oil, this UOA looks pretty good.
Viscosity looks fine, while TBN is still within the useable range.
I'd personally use a thirty or forty grade oil in this engine, as most would have done in 1985, especially in a climate like yours, but the old dear appears to have done very well on a multigrade which didn't even exist when it was built.


+1. Couldn't have said it better myself.

 

[Gokhan]

I agree that it did fairly well with 5W-20, which didn't exist for many years after the car was built, and the OEM spec was 10W-30, xW-40, or xW-50.

Nevertheless, this UOA is showing an interesting effect on the antiwear-film destruction when you change oil viscosity and/or type. From how much Zn is in the oil in comparison to the VOA, the 15W-40 HDEO antiwear film got destroyed and all the Zn went into the oil, This also caused Fe to come out of the old film, as the antiwear films contain P, Zn, and Fe at the minimum. The question is how good is the new antiwear film formed by the thin PCMO? Is it as thick as the HDEO antiwear film? Is it as strong as the HDEO antiwear film? Is the thinner oil will be less effective in controlling wear at the piston rings and bearings because of less viscous force against the slapping parts? Will the Cr, Fe, and Cu numbers get lower in the next OCIs or will they remain moderately high?

By the way, I seem to be getting really nice performance out of the Toyota 0W-20 SN, which seems to be a Group IV/V oil from its intensely nauseating odor. Unlike PYB, it doesn't have boron, which stuck to the films on my metal surfaces according to the UOA and VOA, and since it's a top-tier oil made my ExxonMobil, it's guaranteed to have the Infineum trinuclear moly. PYB didn't seem to be very good at reducing friction, but this could also be because of all the stuff that came out of the HDEO antiwear films into the oil, which is now gone after the oil drain. Toyota 0W-20 SN seems to be resulting in smooth engine with little vibration or labor at any RPM. In 3,000 miles, I will do a UOA and see how things are now with the Toyota 0W-20 SN synthetic.

If things drastically improve, it would also be a lesson on not to change the oil viscosity, type (PCMO, HDEO, synthetic, dino, etc.), or brand back and forth due to antiwear-film stripping.

 

[lexus114]

Originally Posted By: pbm
I would run 5w30 in the winter and 10w30 in summer in an 85' Corolla (especially one with over 200K).
I'm nearly certain that Toyota didn't backspec 5w20 that far back.



They didnt.