Oil coking? How will I know?

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One of the concerns with VW TDI engines is ring plugging and oil coking in the turbo.

When reading an oil analysis how can I tell when the oil is coking or the rings are plugging?
 
I'm sure Terry will correct me if I'm wrong, but I think that if the oil is coking, you'll see heavy oxidation going on, and the nitration will be pretty bad also.
 
Thanks Patman

Looks like I'll have to give up my cheap CAT oil analysis since they don't give me oxidation or nitration results.

Terry does your analysis include these two items?
 
Neil,

There is really no way to tell from oil analysis, until your piston rings become stuck by coke deposits. At that point your iron and chrome levels will go through the roof and you will have generated a condition that isn't reversable, aside from disassembliing the engine and physically cleaning the ring grooves.

I'd stick to the VW recommendation on this one and use Mobil Delvac 1, 5w-40 or the Amsoil 10w-40 synthetic in the TDI motor. I don't think a 30% PAO blend will cut it in this particular application ....

TooSlick
 
Heck yeah,
banghead.gif
I can tell if we are coking the oil BEFORE it sticks rings etc. ! Why do analysis if we can't stop a problem before it shells your motor ?

Before you see the wear Slick describes, I will see increased nitration, soot and solids and others I wll not give away here, compared to levels in the same type engines tested that alert me to a problem.

Yes Neil our kit provides those as well as the insolubes reading in the Blackstone Dyson # 46 test kit.

I am working with Blackstone to offer a FTIR capability soon.
 
Thanks Terry

Nice to know I can see it coming. I think I'll use your services instead of trying to figure out what that CAT report is trying to tell me.

The CAT system is probably still good for VOAs.

Neil
 
. I don't think a 30% PAO blend will cut it in this particular application ....

There ya go again, Ted, Talk about the whole oil not just the base stock. There is way too many other parts to a good oil that ISN'T considered everytime you discuss oil and IMO, you are failing to consider those items as how it DOES affect the base oils capabilites to hold up especially in situations such as this. So IMO, I would dis agree with your comment if you're refering to Schaeffers as they are about the only ones with that much pao in a blend.

Also, the reverse is true, just because it is a synth base oil, does that make it a good oil?, again, depends on the blend of additives that are included. This isn't to say that m1 or amsoil wont work, but I really don't think your experience with schaeffers is up to the level you could qualify if it is good or bad in that application.
 
bob,

I may indeed be wrong about this, however VW does recommend a full synthetic diesel oil for this application. They issued two TSBs to this effect back in 1999. I am very familiar with this application and have dozens of customers with this TDI diesel engine - it's one of my specialties. the Schaeffers S7000, 15w-40 is an excellent oil, however , so it may work just fine.

I eagerly await Neils oil analysis results.

regards,

Ted
 
You could get an early indication of coking by sending the oil for analytical ferrography. Typically, coking would be seen as larger agglomerates of soot. The viscosity should increase as well.
 
Lubechick

I'm going to give Schaeffer's 15w-40 a try as soon as I complete the initial 5000 mile interval.

Just bought the TDI last weekend. However I expect to cross the 5000 mile mark in late March that will put the first Schaeffer's analysis in May.
 
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