Perplexing oil usage issue. Any opinions welcome

[dirtydannyd]

Hey BITOGers.

I have a 2001 Audi A4 2.0 ALT engine (no turbo). Car has about 170,000 km (105,000 miles). Temp is Melbourne Australia so as cold as 5 deg C (41F) overnight and 30C (86F) during the day. Nothing too crazy. Driving is 50/50 freeway/city. Driving style is moderate to sporty.

Previously used Shell Ultimate 5W40 as it's a VW502 spec oil. Before that Mobil 1 0W40. Oil usage on the car has always been roughly 1 liter every 2,000 - 3000 km (1200-1800 miles). Yes reasonably high. I've just lived with it and topped it off regularly. I have tried other VW502 spec oils and there has always been a fair bit of oil consumption.

Recent service was with Shell Helix HX7 10w30. This oil has no mfg approvals but is API SN and ILSAC GF-5. So far, few thousand km's later and oil usage is 0. Personally, I find this a bit funny as the new oil is a 'thinner' oil (10w30 is 10.49 cSt at 100C and VI of 149 for as opposed to 5w40 is 13.1 cSt at 100C and VI of 168).

What's the go with that?

Also, will the 10w30 last the 15,000km (9,300 mile) service interval?

Any opinions welcome.

Cheers.

 

[demarpaint]

There are cases where going "thinner" actually reduces consumption. Shell did a study on it. IIRC they said depending on what was causing the consumption, rings in particular, going "thinner" could help. Maybe someone here can link to the article, I can't find it.

 

[bigt61]

It's possible the Helix HX7 has a better tolerance to burn off, blow-by and is more compatible with engine seals. Some cars just stop using as much oil when they get older. IMO it should do 9k miles with no problem.

 

[Ded Mazai]

I have seen this many times when a mineral (higher mineral content) oil reduced the consumption. I cannot explain the mechanism but I am convinced that it is the oil base what makes the difference. And this only happens in an engine which burns some oil. I would guess a mineral oil in the piston ring area burns quicker and is replaced with a fresh oil faster creating a better seal. Also I noticed that a mineral oil gets darker much slower in such engines.

 

[dirtydannyd]

Originally Posted By: demarpaint
There are cases where going "thinner" actually reduces consumption. Shell did a study on it. IIRC they said depending on what was causing the consumption, rings in particular, going "thinner" could help. Maybe someone here can link to the article, I can't find it.


Really? I've never heard that before. As if the whole question of oil consumption wasn't difficult enough!


Originally Posted By: Ded Mazai
I have seen this many times when a mineral (higher mineral content) oil reduced the consumption. I cannot explain the mechanism but I am convinced that it is the oil base what makes the difference. And this only happens in an engine which burns some oil. I would guess a mineral oil in the piston ring area burns quicker and is replaced with a fresh oil faster creating a better seal. Also I noticed that a mineral oil gets darker much slower in such engines.


A while ago i used Mobil Super X2 3000 5w40 which i thought was a mineral oil and consumption was the same as Mobil 1 and Shell Ultra.

 

[4wheeldog]

Well......You finally got that Audi's rings to seat. Cheers!

 

[Kuato]

Originally Posted By: 4wheeldog
Well......You finally got that Audi's rings to seat. Cheers!


There you go... or maybe you were using the oil at startup, and the 10w is thick enough to prevent that when the engine is cold ("cold" being relative)

 

[SR5]

I forgot about this oil until you mentioned it. I too had an old Audi the used oil. The mechanic put Shell HX7 in it because he said it was designed for older cars to help reduce oil consumption. It's a semi-synthetic.

It did help a bit, but not as much as Penrite HPR oils. I can't recall the HPR oil weight I used right now, probably on the heavy side.

 

[dirtydannyd]

Originally Posted By: Kuato
Originally Posted By: 4wheeldog
Well......You finally got that Audi's rings to seat. Cheers!


There you go... or maybe you were using the oil at startup, and the 10w is thick enough to prevent that when the engine is cold ("cold" being relative)


With regards to using oil at startup, isn't even 5w waaaaay thicker than a xW40 at operating temp?

Also the hx7 10w30 is 72.3 cSt at 40 deg C whereas the Ultra 5w40 is 79.1 at 40 deg C which confuses me more.

 

[dirtydannyd]

Originally Posted By: SR5
I forgot about this oil until you mentioned it. I too had an old Audi the used oil. The mechanic put Shell HX7 in it because he said it was designed for older cars to help reduce oil consumption. It's a semi-synthetic.

It did help a bit, but not as much as Penrite HPR oils. I can't recall the HPR oil weight I used right now, probably on the heavy side.


Yeah cheers. How long did you leave it in your audi for?
My next step was to use a Penrite oil. The hpr range is usually a grade thicker. Guessing they put in more VI modifiers.

 

[SR5]

The Shell HX7 is obviously working for you, I would stick with it.
I changed it out every 10k KM or 12 months. My Audi / VW mechanic seemed happy with that.