oil sludge

[w261w261]

I just got a letter from VW about my 2004 Passat 1.8T. VW has extended the warranty to 10 yrs/120k miles in response to a class action suit regards their oil sludge problem. Of course, you have to prove you've done all oil changes on time, with receipts. In my case, I'm virtually at 120k, so it doesn't matter.

1. The Passat has always had full synthetic oil. From what I can gather, synthetic does not produce a sludge problem. Is this true?

2. Our cars don't seem to be bothered by sludge, or any older cars for that matter -as long as they've had the oil changed regularly. Is this because the older engines run at lower temps or have looser tolerances or what?

[2oodoor]

That is a real bulletin. This seems like dejavous, didnt this happen to the same vehicle in like 99 or something?

[DBMaster]

There was a recall on some years of Toyota Siennas for oil sludge issues. That was a few years ago.

This article explains the issue a bit: http://www.schleeter.com/oil-sludge.htm

I do disagree with the guy regarding 3,000 mile oil changes. If I were on conventional oil I would go 5,000. I have been going 10,000 since 1994, and 7,000 before that with no ill effects and zero sludge (using synthetic).

[Oldblueaccord]

Its the way they vent there motors due to emission. A Lot of the Toyota,Chrysler motors have recalls on it. There some revised valve covers and such that are supposed to help.

Biggest thing is how many miles you drive. Short trips are really hard on these new sludge motors. They build up moisture in the top end of the motor and it needs to be run hot for a while to burn it back off. if you just drive short trips you may want to try to get in a long trip during the week to get the motor good and hot.

wp

[Dr_Snooz]

I remember when a lot of auto-makers started saying you didn't need to change your oil but every 10k or 15k miles. My oil always gets dirty at 5k, so that sounded like crazy talk to me. Apparently, they did this to game total-cost-of-ownership numbers calculated by car mags and websites. That number goes down a lot when you're only changing oil every few years. I knew there would be a downside, but I didn't know what. I guess this is it.

[DBMaster]

Well, in that case, my engine may only last half a million miles instead of a million. Appearance of the oil means very little. You can't know whether or not it's "dirty" without oil analysis. Oil in diesel engines looks bad within a couple thousand miles, but is fine. I have seen my lower end, valve cover, cam, etc. using the 10K mile oil changes and everything is super clean. My compression is good and my fuel economy is just as good as it was in the 90's (after the change to reformulated gasoline in the Dallas area). So, you'll NEVER sell me on the "value" of changing oil prematurely.

[PeterNtheWolf]

I just got a letter from VW about my 2004 Passat 1.8T. VW has extended the warranty to 10 yrs/120k miles in response to a class action suit regards their oil sludge problem. Of course, you have to prove you've done all oil changes on time, with receipts. In my case, I'm virtually at 120k, so it doesn't matter.

1. The Passat has always had full synthetic oil. From what I can gather, synthetic does not produce a sludge problem. Is this true?

2. Our cars don't seem to be bothered by sludge, or any older cars for that matter -as long as they've had the oil changed regularly. Is this because the older engines run at lower temps or have looser tolerances or what?
the sludge is unburned gas residue, or Carbons that are collected in the oil, so the point of a oil filter is to strain and trap them. Today's new cars, oil intervals are much higher, up to 15,000. Every car will have a rate of this process.

[gp02a0083]

uh i dunno what to say on this topic , i have and my father has always changed the oil in 2500- 5000 miles intervals. I can believe that the synthetic stuff can go longer in between changes, but conventional oil i wouldn't want to toy with it.

alot of people go by the oil looking dirty and what not, really the only thing you can see with this is if the oil is off color , possibly indicating that the engine is burning a bit of oil. As another member said diesel's always look like they are running with dirty oil , but that's just because of the design of a diesel engine, they kinda burn oil on purpose.

From a chemists point of view and with my mechanical knowledge, oil should be changed semi-often, more so with conventional oil. The amount of detergents and additives that are in the oil help keep the internals clean and provide sufficient lubrication. Over time (with conventional oil) the chemical structure will eventually break down, this is accelerated by the consistent churning and heat cycling from the engine itself. Just think about some of the tolerances the the oil also has to flow through. Synthetic oil's have different polymer's in them along with different additives to sustain a level of lubrication. I learned alot of this from one of my friend who is also a chemist who works for Bel-Ray (motorcycle lubricants) down the road from my house.


why do you think Castrol has the slogan , " liquid engineering"