Two Toyota questions

[Ken2]

1) What is the connection between the camshaft drive gears shearing the oil and the creation of the sludge or gel?...or the process that creates the gel from the sheared oil? 2) On an oil analysis report, what shows the beginning of the gel or sludge?...Oxidation increasing?...By the time the viscosity starts increasing, is it too late...gel already starting? Bob's photos of the sludged Toyotas are interesting...I'd expected the usual heavy brown/black sludge, not that almost-translucent brown gel. Ken

 

[TooSlick]

Ken2, I suspect what is happening is that you are shearing the VI modifier and these sheared polymers are then subject to attack by oxygen/heat. The oil itself isn't badly degraded by combustion by-products after 3000-5000 miles, so it's still fairly clear. If you cook some conventional oil in a saucepan for a couple of hours, it would probably look something like this. Some of this sludge is also due to accelerated nitration, based on the oil analysis data I've seen. This is a different degradation mechanism then overextending your oil change intervals and creating sludge when the antioxidants are depleted ....that's the greasy stuff you are used to seeing. TS

 

[Pete]

Ken, He's right. Gears will shear the VI improvers--long polymers which stretch when warmed. This will result, first, in a thinning of your oil out of grade (say 5W-30 to 5W-20). Then, this thinner oil will cause more friction and heat; this will eventually result in the oil "cooking," into a gel. Pete (2002 Sienna with 20,000 miles)

 

[BOBISTHEOILGUY]

I wonder where I've heard that before?

 

[Ken2]

And what'll show in the analysis? Ken

 

[Pete]

Thinner oil, first.

 

[TooSlick]

Ken, The four things I've seen with the V-6 are: 1) significant thinning of the oil when tested @ 100C - on the order of 15%-20% 2) rapid TBN depletion - ie TBN's in the 6-8 range in 7500 miles with Amsoil 3) greatly accelerated nitration - 50%-60% in 7500 miles with Amsoil 2) somewhat accelerated oxidation - 20%-30% in 7500 miles with Amsoil Wear rates look normal, provided you don't overextend the particular formulation you are using. This engine is simply bad news from the standpoint of oil degradation ... TooSlick Dixie Synthetics

 

[Greg Bohn]

quote:

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Originally posted by TooSlick: Ken, The four things I've seen with the V-6 are: 1) significant thinning of the oil when tested @ 100C - on the order of 15%-20% 2) rapid TBN depletion - ie TBN's in the 6-8 range in 7500 miles with Amsoil 3) greatly accelerated nitration - 50%-60% in 7500 miles with Amsoil 2) somewhat accelerated oxidation - 20%-30% in 7500 miles with Amsoil Wear rates look normal, provided you don't overextend the particular formulation you are using. This engine is simply bad news from the standpoint of oil degradation ... TooSlick Dixie Synthetics

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I have a 2002 1MZ-FE in my Toyota and have been trying to figure out why the oil reports always come back with the oil flaged as too thin. I've noticed the results seem to show the TBN and Viscosity aren't what you'd hope for. My results are:

code:

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5W-30 'Dealer' Bulk oil

Date:          08-12-02  08-26-02  12-08-02  12-12-02  12-20-02

Engine Miles:     1,528     1,723     2,772         -     2,862
Oil Miles:        1,528       195     1,244         0        72
 
Visc. (cSt)        8.46      8.94      7.90     10.77      8.58
TBN                3.06      6.23      1.99      7.59      6.18
Oxidation (Max 30)    3         4        15         6        <2
Nitration:(Max 30)    6         6        13        <2         5

Silicon:            264        64        62         3        17

Boron:               21       121        81         9        27
Molybdenum:          45        68        55         4        15

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In two cases, supposedly 'young' oil only 195 and 72 miles old is much thinner than I would have expected. The results always showed Fuel dilution <2.0% and water <0.10% which is the lowest this lab reports. I threw in some additive/silicon numbers as it seems to show that the dealers bulk oil is different between the last two batches I got. And that the oil appears to have actually been changed. The car currently gets frequent short trips of about 5 minutes, as I live close to work. But, the engine temp. gauge usually shows the car is almost at normal temp when I get to work. In the summer it usually did reach normal temp. The 12-12-02 0 mile result is supposed to be what they filled it with in a change right after the 12-08-02 sample was taken. So the 72 mile results are supposed to be the same oil, only used a week or so. The 1,723 and 2,772 engine mile results are supposed to be from the same change period. The Oil was changed right after 2,772 miles, but not after the 1,723 engine mile/ 195 oil mile sample.

 

[Pete]

Greg, those numbers don't look too promising! I wonder how a bottled (you know what it is) oil would do, and how a 10W-30 would fare?

 

[Giles]

Greg, I recommend posting your results in the used oil analysis forum to get some insight on your results. You might have one of those Toyota engines that shear's the oil causing it to thin out. If so this oil isn't up to the task based upon the viscosity numbers. You also might have had an intake air leak because of the elevated Silicon (although new engines tend to have some silicon). I would recommend you select a good quality oil and either do your own oil changes, or take the oil with you to the dealer to have them change it for you.