moribundman

Remember when you said you had higher oil consumption with thicker oil compared to thinner oil? The cause for this phenomenon may be attributed to ring tilting. According to a Shell Global test, oil viscosity affects ring movement.

In short:

- thicker oils can cause ring tilt, resulting in more blowby

- thinner oil can give higher top ring oil film thickness than for example a 15w-40

- keeping the ring area clean from deposists is important. CI-4 oils do a good job at that.

Ghostfire

I had higher oil consumption with 10w-30. Now I have almost no oil consumption with 5-40. .5 liters in 3k and thats with a very slow oil leak.

moribundman

- volatility of the oil (denoted by NOACK evaporative loss number)

- viscosity at low and high temperature

- ring design -->blowby

- ring condition and deposits in ringland --> blowby, ring tilting

- driving style

Until 70k mile my oil consumption was ridiculously low, and even with 10k mil oil change intervals the motor consumed 1/3 qt tops. Shortly after the car developed various oil leaks. Dealer and shop never fixed them properly, and I've been leak-free ( :-P ) only for about 10k miles. My current oil consumption is about 0.5 qt/1000 miles. I know my oil consumption is easily cut in half by cruising granny-style.

Whether or not thicker or thinner oil reduces oil consumption in a particular can be detrmined only by trial and error, but more often than not thicker ("hot viscosity") oil will work better.

VAP

new owner regarding excessive oil consumption. Maybe I was tilting those rings with my right foot!?! ;-)

BTW: ARX teatment is completeley finished and as we suspected would happen there was no change at all. Wasnt even worth re-shooting a pic as inside valve cover was identical. Total waste of $ and time. Wasn't a biggie cost-wise but the friggin treatment went on FOREVER!! I'm now running Elf synthetic oil in a 5-40 configuration and have been meaning to get you all the mumbo-jumbo stuff off the bottle to run by you and still plan on doing that soon as this short-term memory thing takes a break.

moribundman

Tell me about it. I go for for a nice drive and that damn 12v gobbles fuel and oil like there was no tomorrow. Elf, eh? How'd you get ahold of that exotic stuff? When you get a chance I'd love to hear what it says on the bottle.

Mr.D-'97 A4q 12v

And I actually got 21mpg this tank but probably because I've been taking it easy because A) my tires suck horribly and need to be replaced and B) it has been raining (see A).

VAP

I dont know all the details other than I get it dirt cheap ("relatively" speaking of course). They carry it in 5-W40 and 10-W50. But I wont put a drop of it in the new motor until enlightened as to its make-up. I did notice it has a VW spec but I have no idea which one.

I'll try to remember to get that to you ASAP.

moribundman

Chances are I can dig up a virgin oil analysis

moribundman

ELF EXCELLIUM DID 5W-40 meets the elusive VW 505.01 spec. A 100% synthetic product for 2004+ VW TDI PD engine. Pump injector engine require a high performance oil mainly because of the extreme pressure on the injector pumps.

Also meets VW 500.00 (gasser) and 505.00 (diesel). Not sure why it doesn't meet VW 502.00. VW 500 has gone the way of the dodo. Eaten by Dutch settlers and their dogs. ;-)

moribundman

If not, be quiet and drive. ;-)