rodneyh1 said:
If my oil level creeps up any more, I'll do the analysis early. If it looks steady, I'll hold off to 5K.
Rod
Hold on everybody! Step back a minute and chill.
The premise I am reading out of your statements here is that you are concerned about a rising level of oil indicating increasing oil dilution, with biodiesel as the culprit.
But think about it: Why would biodiesel sneak past the piston rings into the crankcase where regular ULSD would not....? The only valid concern I have heard about using biodiesel thus far has been that small amounts, or even any amount, of biodiesel in engine oil will eventually damage internal reciprocating / rotating engine components by displacing proper lubrication (due to polarity of methyl ester molecules vs polarity of engine oil and specific high pressure additives). This concern could well be valid (though I consider it prematurely paranoid, as I don't think any OEM would consider an amount of measured oil dilution harmfull enough to seriously displace lubrication as acceptable during initial engine testing. They would not approve an engine for production if it had such a flaw - though major mistakes like this can occur, even on this level).
But there is no reason that biodiesel, as a fuel, will cause a noticeably larger gross amount of oil dilution. It will burn in the cylinder exactly as regular ULSD will. The only contention, and we only have one that I know of, is a less than substanstial claim of a VW tech. paper stating that the exhaust aftertreatment regeneration strategy of the CR engine involves an injection event after combustion has ended, thereby rendering some amount of oil dilution likely.
AND at that, only if a significant amount of oil makes it onto the cylinder walls, unburned, and then past the piston rings and mixed into the engine oil. I personally find this an unlikely scenario. The injection spray pattern will certainly be tight and focused on the piston bowl. Even if the piston was a 1/4 way down the bore, it shouldnt hit the cylinder walls. Anyway, getting off track here.
Theres no reason that Biodiesel will specifically dilute your engine oil MORE than regular diesel. The only concern is that this SAME amount of dilution will be detrimental to engine components. If you do have an observably rising oil level, you'd be screwed no matter what fuel you are using, and you would have a major sealing issue in at least one cylinder. Wait, would you stop using biodiesel only to protect your warranty? That might be worth doing, lol.
BUT, please dont be worried, or spread worry, about a mystery rising oil level as caused by biodiesel. My geuss for the high oil level would be that before the rings break in, some is going to sneak into the cylinder and burn on the cylinder walls during combustion. This is normal (ever had a car that drank oil slowly? If it didnt leak onto the ground, this is where it was going). VW may know this, and perhaps slightly overfill the engine for delivery before proper break-in has occured. Thus by your first scheduled oil change, the level hasnt dropped to the low mark of the dipstick.
Please wait until some time and miles have passed to raise concern. Oh and BTW, every engine dipstick is meant to be checked for a warm, just run engine ,where the oil has been pumped up into the cylinder head, turbo, coating all components, etc. When your engine sits and cools, it all drains back into the oil pan and the level appears higher.
personal note: I want to commend everyone using biodiesel on the 09 engines! You are brave pioneers, yes, but honestly if you live in a warm climate I don't think you're risking much at all. Certainly not 26 thousand dollars. Worst case, a $2-4k engine overhaul. Some amount of increased maintenance is WORTH IT for a vehicle that runs on zero petroleum, IMO. Kudos. btw, I specifically bought an '03 ALH engine VW instead of the PD because internet fear-mongerers cautioned against using biodiesel in the PD. Shame on them, as we all know better now. How many of those same people jumped on the fear bandwagon this go-around.....?