Mobil 1, 0w40, 5k OCI, '99 Audi A4 1.8T

[e40]

This is my third UOA on this vehicle. The first UOA was with unknown dino oil (when I purchased it), and the remaining two are with the Mobil-1. Mann 940/25 oil filter.

I suspect that I have a PCV system problem, so I will be replacing every valve depicted in the PCV diagram. (Oil is being forced through the oil filler cap). Not enough oil comes out to necessitate adding make up oil, but it's enough that is slicks the sides of the engine.

 

[buster]

If B/S Labs is showing 2.8% fuel, you know it's very high and most likely higher than that. I do think replacing the PCV valve would be a good move.

 

[JAG]

Yeah I'd bet its PCV system is very clogged up. This is the imfamous VW/Audi 1.8T (longitudinal) sludgemonster engine. The high fuel dilution, high insolubles, and especially the oil blowing out of the oil fill cap are almost a sure sign.

I have the less sludge-prone 1.8T transverse engine and only ever used synthetics, usually at 5k miles or less but sometimes longer, and still clogged up the PCV system. It cost me $500 in parts and labor to replace the clogged parts.

I pushed the engine hard, long, and hot on many occasions and this was likely how I was able to get enough deposits in the PCV system to clog it up, in the less sludge-prone 1.8T.

 

[e40]

Well, the PCV system definitely wasn't in the best shape. After changing these components, I'm no longer getting oil pushed out the filler cap. So, hopefully the next UOA will look better.

This long hose had a big crack down the middle, and basically disintegrated as I removed it from the engine:

A shot looking inside the hose:

I replaced all 4 check valves, one of them was rubbing on a bracket, and wore completely through:

 

[Doug Hillary]

Hi,
this is a good report on the lubricant. Fixing the PCV system will attend to the other matters as you have noted

Porsche M96 engines have a "similar" PCV system - they are the source of problems too as the cars get older, including excessive exhaust smoke (with little oil consumption) and this annoys many owners, it a sure sign of failure

 

[JAG]

That picture of the inside of the hose is cool. The inside of my 1.8T's PCV hoses appeared to be similarly "defecated in".

 

[CBR.worm]

I'm about to do this job on my wifes '04 A4 1.8T w/ 48K

Hers is not pushing oil out the cap, but out of every other seal.

I have all the parts, just need a dozen or so hose clamps and to get busy. I just sent a before oil sample to Blackstone - it will be interesting to see the results for the next OCI after everything is replaced.

Her engine doesn't seem to be "sludged", but there are a lot of deposits all over everything. It kills me to see this mess on a car with Mobil1 and such low miles and regular oil changes. And no short trips. Luckily we have a good dealer who does every other oil change and really helps us out with service issues.

 

[audi_guy]

Check out my last UOA on my 2000 A4 1.8t:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1249681#Post1249681

It had 1.5% fuel dilution and I had the PCV system serviced and replaced the coil packs. Fuel dilution dropped to
You also have the typical high Iron from Mobil !. Mine dropped when I started using Castrol GC 0W30.

 

[Hokiefyd]

On this report, why are the Blackstone "correct" viscosity values for this oil 11.6-14.8 cSt? Isn't the "correct" viscosity range for a 40W oil 12.5-16.3 cSt?

Likewise, is their SUS range truly correct as well?

 

[Gary Allan]

Originally Posted By: Jason Adcock
On this report, why are the Blackstone "correct" viscosity values for this oil 11.6-14.8 cSt? Isn't the "correct" viscosity range for a 40W oil 12.5-16.3 cSt?

Likewise, is their SUS range truly correct as well?


It's an average of what the data base pukes out. I assume that they have some software that kicks out really odd extremes, but if most Audi 1.8's deviate between 11.6 and 14.8 ..that's what they put up.

Now if all Audi 1.8's used M1 0w-40 ..then the visc range would be <12.5 CST. They could never have a UOA that was a 40 grade unless it was in storage.

 

[Hokiefyd]

Oh...so it's not an empirical "allowable" number...it's simply the average for that engine type? That makes more sense.

But back to my original question -- that 0W-40 HAS sheared out of grade in this UOA, correct?

 

[buster]

Yes, it is now an upper 30 grade oil due to high fuel dilution and the break down of the viscosity modifier. 2.8% fuel dilution found by Blackstone Labs means it's very high.

 

[Hokiefyd]

It's not even this UOA. Almost every M1 0W-40 UOA I've seen has demonstrated that the oil has sheared down to a strong 30W. That's not necessarily a bad thing (most engines run well on a 30W oil), but I was having a discussion with a friend on another forum, and we had a difference in opinion on whether the M1 0W-40 was necessarily prone to shearing down. To me, based on what I've seen, it is.

 

[Steve S]

The oil seems to work well though.

 

[Gary Allan]

Yes, it's a great oil. It's just that you do the final finishing process in the engine. It's hard to argue with the results.