Shear with Gears

GW

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Bob, I remember you saying in another post that the timing gears in Toyota V6's shear the oil. I agree with you that this is not a common design for gasoline engines but, in diesels this is very common. Diesel engine oils apparently do not have this problem, (withstanding shear with gears) and I was wondering how they differ with gasoline oils in this regard - do they use better VI improvers? If this really is the root cause of sludge production in Toyota V6's, and if diesel engine oils really can withstand shear better, would it be not be wise (for those not paranoid about phosphorous) to use a diesel oil in these engines instead? (i.e. 5W30) [ June 23, 2002, 11:01 AM: Message edited by: GW ]
 
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Good point Gw and come to think of it, I have 2 people running our 15w40 oil in their toyotas and have told me they do anywhere from 8-12,000 mile drains. Of course it really concerned me and expained the sludge issue and really expected to see that but when I examined inside the engine with the use of a screwdriver(as I mentioned before), I found nothing.. So there might be something to that when you think about it. As for the diesels having a gear system in the overhead like a toyota does, I don't recall seeing that. Here is a pic of a toyota with the gear assembly I am reffering to. Keep in mind, this is only one side and there is a second head on this engine with another like it.  - This picture was taken on a 6cly toyota engine with less than 15,000 miles and had been cleaned with a new wins engine cleaning machine for 45mins. [ June 23, 2002, 01:11 PM: Message edited by: BOBISTHEOILGUY ]
 

GW

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Bob, I do not think it matters whether the gears are used in an overhead cam design or not.....the fact is that many (or most) diesels do use gears to drive their cams and they are lubricated, of course, with engine oil. The question still remains: How do diesel engine oils differ from gasoline oils with respect to shear resistance? (if at all) Anyone? [ June 23, 2002, 03:58 PM: Message edited by: GW ]
 

MolaKule

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Here is just a theory, since I don't know the engine design specifics of the Toyota engine in question: Diesel engines have high volume, low pressure oil pumps (generally speaking). Could the Toyota have a high pressure, low volume lubricating system? Here is what I'm getting to: 1. High pressure oil pump shears oil. 2. Low volume oil stays in one place too long and isn't allowed to reject its heat, thereby oxidizing the oil much quicker.
 
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atually, I think Mola just hit on something that explains why maybe a diesel engine lasts longer. The v6 toyotas have less that a 5qt capacity as a diesel engine has a much higher volume of oil therefore not destroying it as easliy as in the toyota engines with such a low capacity. The pressure and volume on these engines (v6)are not much if any different than any other gas engine. The picture above is an actual v6 engine and the gear assembly used in that engine. As stated before, less than 15k miles on whole car. This was not uncommon.
 

MolaKule

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Excellent Point Bob, Oil sump capacities have decreased over the years. My '86 burb takes 7 quarts for an oil change with filter, whereas most newer cars and trucks have 4.5 maybe 5 quarts sump capacity. And it is not uncommon for diesel engines to have 17 quarts of oil in the system. The more mass of oil, the more opportunity for the oil to reject heat, the more additive potential, the better the dirt and particle dispersion, etc.
 

GW

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Bob, Are we off the Shear with Gears theory now? What do you think about diesel engine oils not succumbing to this phenomenon? Are the VI improvers of a better quality than those used in gasoline formulations?
 
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I agree with the oil capacity on diesel engines. On a Power Stroke Ford 94.5-98 14 qt. and 98.5-present 15 qt. Add a bypass filter and the capacity increases from 1qt to 6qts depending on the filter. Over 1.2 million of these engines (Navistar) on the road and I have never heard of a sludged engine on them. And I live on the diesel sites when not on here. Now for the oil pressure, standard engine oil pump for the engine and turbo, has a second high pressure pump in the valley, (V-8) for the injectors. At idle the typical pressures are 500 psi at idle and 3600 psi at full load acceleration and some where in between at cruise. So an oil with very good anti-foaming properties has to be used. And I can assure you that the engine will run like heck if this property is depleted. Good 15W40 oils that work great are: Rotella T, Delo 400, Mobil Delvac 1300 for dino, Schaeffers 15W40 Supreme for semi-synthetic (listed that way), and Amsoil 15W40. There are others that meet the Ford spec. CG/SJ, CH/SJ (dual rating is speced) It is generally accepted that the diesel oils have a very robust additive package because they have to keep the soot in suspension until the oil is changed. IMHO if I had a sludge problem you can bet I would use dual rated diesel oil, and most can be purchased in the 5W30 or 10W30 wt, but hard to find and usually have to order from a Distributor.
 
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The majority of what I have was SJ/CH-4, now SL/CI-4, and I have never seen shear in any gasoline engine that I've analized. The only shear I've seen is in Nissan Diesels, where my AMERICAN brand (Group I) shears out of grade around 300 hours, Pennzoil shears well before 200 hours. For his next changes I'm discounting a drum of Delo 400 for a major customer (180 pieces of equip)(5 Nissans) just to see how it hold up on these engines.
 
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GW, A gear drive is more common than you might think. GM inline 6 cylinders,230,250,292 and the Ford 300 ci inline used them for many years. I do not think this is THE problem with the Toyota motor at all. The valve springs are ultra light in terms of open pressure,the helical cut gears are only to reduce the amount of noise.That type cut does increase the side load though but should only affect the thrust side on the camshafts/head I would like to see the exhaust gas temps for all the cylinders and also the exhaust cam centerline because it looks as if the motors cylinder head temp might be the blame yet the pics shown it might have had water in the oil.Very ugly! I don't believe that high,low or no oil pressure would contribute to this. Many other things could be to blame,,think about drain back problems as well? Those gears are throwing oil every where,no doubt but is it affecting drainback? Who knows? This is the first I have heard of the Toyota problem and want to be sure I don't type myself into a corner which I have done before [Smile] I guess time will tell an what actually cause this problem but like the others,I would frequently change the oil if I owned owned of those motors and it would definatly have a Diesel type oil in it if it were my motor [ June 24, 2002, 10:39 AM: Message edited by: dragboat ]
 
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My '98 Honda VTR motorcycle calls for oil changes every 8,000 miles. I guess Honda isn't too concerned with shear. You'd think if shear was a big problem you'd see it in this application. I'm using Redline 10-40w and change it every 4,000 mi which is about every 6 months. I'm too cheap to do an oil analysis. [ June 24, 2002, 08:34 PM: Message edited by: satterfi ]
 
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I'd have to agree that something other than the use of gears in the Toyota FE head design engines is to blame for the sludge problem. There are two engines that have had some sludging issues for the 1997 through 2001 model years, the 5S-FE and 1MZ-FE. These are the Camry four and six cylinder engines respectively, with the four of iron block and aluminum head construction and the six of aluminum block and aluminum head construction. I'm not aware of sludge issues with the 3S-FE (1987 to 1991 4 cyl Camry), 2VZ-FE (1987 to 1991 6 cyl Camry), 5S-FE (1992 to 1996 4 cyl Camry) 3VZ-FE (1992 to 1993 6 cyl Camry) and the 1MZ-FE V6 used from 1994 to 1996. All of these engines have FE heads which have a belt driving one cam which in turn drives the other cam through the use of the gears shown in Bob's picture above. The VZ series 6 cylinder engines, while using the FE head design, have cast iron blocks by the way. The 1997 1MZ-FE engine power output slightly increased over the 1994 through 1996 version of this engine and I believe that the engine went to LEV status at that time as well. Perhaps operating temperature was increased for emissions control factors and that coupled with the head design is causing the sludging. Additional food for thought, the 5VZ-FE six cylinder in the Tacoma and Tundra has the same FE head design with gear drive for one of the cams but trucks are held to different emissions standards. I'd hazard a guess that operating temperature is the major culprit coupled with poor maintenance. I have a 1991 Camry with the 3S-FE and 1999 Camry with the 1MZ-FE and neither has had a sludge problem (3,000 mile oil changes on both).
 
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quote:
Additional food for thought, the 5VZ-FE six cylinder in the Tacoma and Tundra has the same FE head design with gear drive for one of the cams but trucks are held to different emissions standards
Here is more food for thought as I have already been down this road and can tell you there is more to this shearing than you realize..
  • The engine compartment it tighter, thus creating more heat in the engine compartment
  • 97 on up, Toyota increased recommended oil drains to 5 and 7500 miles respectivly, thus the reason for these years demonstrating sludge more so than pre 97
  • mid 96 is when api changed cert's from sh to a lower level of zddp levels to sj given about a year(97) for engine failures to appear
This is just some of what I have seen and concluded as to why some and not the others. BTW, no sludge has been reported on any of their engines when 3k drains where observed to the best of my knowledge. Only those with 5-7500 miles and Of course this is not to say that there was not anyone not going beyond drain intervals such as the rx300 lexus i refered to previously, as he had 20k on his amsoil oil. (of course this is not to say amsoil wouldn't hold up under the normal drain recommendation but it didn't hold up to 20k in a toyota engine. OH, and one last thought, on all engines that I examined that were sludged and in talking with all the mechanics that were rebuilding them, Not one time did anyone find a pcv valve clogged nor bad, and all were reused when reassembled along with all other emmsissions devices. Toyota from my understanding is changing their recommended oil drains in the new models to 3 to 5,000 miles. Also, it appears another fix they have quitley implemented is to replace any bad (not all) oil pumps with a new one that appears to have a slightly bigger pickup tube as well. This has or has not been proven to fix the problem but is definatly a step in the right direction. [ June 24, 2002, 02:50 PM: Message edited by: BOBISTHEOILGUY ]
 

MolaKule

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Do we have any hard facts in this case, such as: 1. Did the owner prove or just claim to have 20k miles on his oil? 2. What were filter changes? 3. Did this sludged-up engine ever have an oil analysis? 4. What weight (viscosity) of oil was he using, what was his recommended viscosity, and did he ever put any aftermarket additivies in his oil? 5. Driving conditions or habits? Did he/she race with this car/truck? 6. Was this engine in a car or truck? 7. Any known problems with similar engines in similar vehicles? If Toyota IS indeed replacing oil pumps and recommending shorter oil change change intervals, then there very well may have been some design problem in the engine. Sometimes, with the best intentions and the best technology available, we overlook a tiny detail that comes back to haunt us. I think this situation may be a good learning experience for everyone interested in lubrication and engine design.
 
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Bob, Thanks for the additional information on shearing. Owning one of the implicated models makes me very interested in any discussion and facts on this subject. Excellent observation on the tightness of the truck versus passenger car engine compartments and the resultant higher temperatures under the hoods of the cars. I can just about stand in the engine compartment of my truck, but I'd be hard pressed to fit an arm through my V6 Camry's engine bay! It's also interesting that Toyota both is recommending a shorter oil change interval and has changed the pickup tube size on their oil pumps. FYI the dealer that I purchased my Toyotas from has always recommended 3,000 mile oil changes despite what the Toyota maintenance schedule dictates. In their opinion most of the driving that we do in New England equates to "severe service."
 
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2533a: " ... most of the driving that we do in New England equates to 'severe service'." Yep, I'd say that is the case, at least part of the year. Heck, I'd say that applies to [i]most people in most parts of North America. I can't see ever following the "normal" schedule with any car ... using a Group II based oil.
 
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Richard, I suspect your oil change intervals was not the recommended 5-7500 miles but less, correct? Also, it appears that you were using a synth of some sorts which seems to have proven out to have a good detergency. What we had found was anyone that was doing 3k or less, especially with a quality oil, had no problem what so ever. Others doing the recommended drains especially at 7500 miles from bulk oil, had sludge in those engines. [ July 10, 2002, 08:50 AM: Message edited by: BOBISTHEOILGUY ]
 
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