Quoted by Monark,
Bob, what I don't understand is that if all the above is true, why was sludge happening only on the Toyota S (Camry) series 4 cylinder
engine and M (Camry / Sienna van) series V6 engines? Why not also the Z (Corolla) and R Tacoma) series 4 cylinders which also use the
same cam gear design and bucket lifters? In other words, lots and lots of Corolla and Tacoma owners used 5000 - 7500 mile 5W-30 dino change
intervals, yet still did not get sludge and still sailed onto 200,000 miles or more without a problem
Thanks, now that you have made reference to my comments, I'll explain more on this..
First, let me say that after your post, I decided to call Bob who is the Master Toyota tech which also means he is a Master ASE tech. In discussing this with him as he has been one of the tech's I have worked with for well over 8 months on this problem here's his exact words on the techs comments for pcv problems.
"He's full of it like a thanksgiving turkey"
His words not mine. Anyway, I agree. What he(bob) said was there has been no official/unofficial word on the pcv being the cause. A point he brought out made good sense because Toyota is paying a boat load of money to repair these engines and if the pcv was the problem, it would stand to reason to spend 10.00 on this part and line everyone up and change them all out. I agree. Now, the other point, He stated that when they do an SPA replacement, they replace the valve cover and with that comes a new pcv. He checked it against the old ones, and the replacements part number is the SAME EXACT VALVE.
Another point is, the pcv valve will not shear the oil down to a 20w from a 30wt. When or if it clogs, it first creates pressure in the crankcase. This will cause oil to pass by the rings and seals, causing smoking conditions and leaks. It can cause the engine to consume oil thus eventually if not replace exacerbate the demand on the oil and ultimately possibly cause sludge BUT, it would take a long time for this problem to get to that level and engines coming in between 10 and 15,000 miles with sludge is not a candidate for this type of sludged condition.
He also stated that unofficially, he has heard they are going to change their recommendation of oil changes from the 5-7500 miles to the 3-5000 miles and the manual also includes "except in extreme conditions" but does not elaborate on what extreme conditions mean.
Yes the z model cor engines have sludge issues also but is not covered in the SPA campaign, so you don't hear as much about them as you do the others. As for the Tacoma's, their oil sump capacity and air flow across the engine is much different than the other cars/van. Having more oil will in fact allow the oil to last longer as it takes longer before that oil reaches to the offending area thus it doesn't strain the oil as often thereby allowing the oil to last longer drains.
There is no debate, there isn't that many in %'s that is sludged in comparison to those that are. So this also should point to the fact it isn't the pcv because if it were the problem, ALL of them would have the same problem. The ONLY FACTOR that has been consistent in this problem is IMPROPER DRAIN INTERVALS. EVERY sludged engine can be linked to drain intervals of 5k+ miles on conventional dino oil. There is NOT ONE SLUDGED engine that has been drained under 4,000 miles. This is the key problem. The oil drain intervals for these engines recommended by toyota is too long for the standard conventional oils. To get those drain intervals recommended by toyota, you must use an oil that is highly shear stable. So, if you DO find people not sludging up their engine doing 5-7500 mile drains, it is because of the TYPE of oil they are using. It will not be the standard conventional dino.
One last point to mention, Since this problem has become apparent, the newer class GF-3 oils will help in reducing sludge issues because it is more resistant to sludge as opposed to the previous oil group of SJ. This in conjunction of lower oil drain intervals will eliminate the problem and not replacing the pcv.
Something else I forgot to mention is that the drain interval issue, showing oil shearing down to a lower viscosity was all established by using oil analysis. See what kind of tests did he do to establish his argument on pcv problem.
I think the engineers at toyota agree with me that the oil is overtaxed by the extended drain intervals.
Having recieved a nice seiko mens bracelet watch from coporate out of torance ca makes me think they are appreciative for the research I have done and helped establish that the engine is not faulty but a good design and that education for the public on oil drain cylces is very important and lacking in this case.
I think mis leading the public as the cause being a faulty component on the engine is not a good thing as it isn't true based on and established by you and him both since we all agree that more are not sludged than are yet all run the same exact supposed failing components.
[ November 27, 2002, 10:15 AM: Message edited by: BOBISTHEOILGUY ]