Which oil will get me the best MPG with a VW GTI 1.8T?

[rekced]

I have a 2003 GTI 1.8T with around 25k on it. It has always ran around 22-33mpg (33 is rare). This was while using M1 OW-40.

Recently I changed to German Castrol 0W-30. Ever since I converted to this my milage went down 3-5mpg. I burn up 13 gallons of gas in 270 miles. That's barely 20mph with the exact driving habbits, same routs, etc. (Yes, it's the real GC made in Germany)

I am puzzled about this. My car is completely stock. It's not due for any tune ups/services. It has a brand new air filter, etc. My UOA looked great from blackstone using M1.

Is this kind of performance normal for GC?

 

[Palut]

Portland gets oxygenated gas in the winter, so that doesn't help any. Maybe the switch to that coincided with your oil change and is hurting your mileage.

How are your tire pressures?

 

[vad]

Down 3-5 mpg?
Well, it might be normal but couldn't be attributed just to oil.
In addition to possible gas formula changes,
the lower ambient temperatures will reduce your mileage due to more viscous oil in the crankase and transmission, higher fuel/air ratio upon the cold start-up, reduced tire pressure (for every 10 degrees change in temperature, tire air pressure changes approximately 1 psi).

 

[Mr Nice]

Maybe it's time for a tune-up.

 

[Dr. T]

Try BC...

 

[hominid7]

On my old VW Jetta when the mileage would take a dip (usually every 50K miles or so) i knew it was time for a new O2 sensor. Which oil and which grade of gas never seemed to make a difference in my mileage, i got 30 MPG no matter what i did. Then again, mine wasn't a turbo

 

[JAG]

It's not the oil's fault. You should replace your coolant temp sensor (black top) with the new green top version. That is very likely the cause. They dealer has these in stock and they cost very little. When you change it, make sure the coolant is completely at ambient temps or you could get hot coolant splashed on you. Go to www.vwvortex.com forums if you want to learn how to install it or learn more. It might be something else but do this first.

 

[Audi Junkie]

Tests show Syntec 0w-30 SLX gives 2.72% increase in mpg over standard 15w-40. M1 0w-40 has (had) the fuel economy Starburst. My guess is M1 5w-30 EP would do even better.

 

[Willy_G]

I agree that oil weight has a minimal influence on mileage with a 1.8t.

Fuel type and octane will influence mileage more with that engine. 87 octane and ethanol blends will give the worst mileage. High octane and 100% gas would give the best mileage.

 

[gward]

rekced, I don't know if your aware of the vw 1.8t engins but I have a friend right now that is fighting the dealer over oil sludge problems. You can read about it here http://www.autosafety.org/article.php?scid=151&did=963 It is all over the internet so you can search for yourself. I would not experment with any oil unless its full synthetic and make sure you save your receipts.

Good luck,
gward

 

[rekced]

gward- That article seems to point to people who don't change their oil. I've known people who only change their oil once a year, if that. I knew the 1.8T couldn't handle much abuse, but to sludge up with routine 3-5k oil changes using some of the best synthetic oil available?

Please share your friends experience. I would appreciate it.

 

[LarryL]

You might be expecting too much from your oil. A thinner oil should do better, but a different, thicker oil just might help the rings seal better and help the engine get a little more work out of the same amount of gasoline. A repeatible test is hard to do, when you have to use the car for everyday transportation. On a test truck, we had to resort to removing the saddle tank, and weigh it before and after, to help remove as many variables as possible. Filling the tank and using volume, instead of weight is more practical but not as accurate.

 

[gward]

VW has had his car for 3 weeks now trying to fix it. He had his oil changes done at Jiffy Lube every 5k miles but was only using dino oil. They said he should have received a letter in the mail stating about the problem with oil sludge and to only use full synthetic oil. He claims he never received the letter in the mail (he had moved in the past year) so the dealer kept the car for about a week then they told him they would do the repair under the extended warranty. Under the extended warranty VW claims they don’t have to give you a loaner car. So the dealer now has had the car for 3weeks and telling him they don't know how much longer it will be because they needs more parts! He ask them if they would run a engine cleaner through the car to remove the rest of the sludge and the service manager said NO because VW headquarters doesn’t think it necessary. The service manger (personal opinion) told him to use Auto RX and go through the cleaning process after he gets his car back.

 

[thunderchild]

Use Auto RX. Well it sounds like that is the first bit of intelligent information that dealer has given your friend.

 

[q2bruiser]

quote:

---

gward- That article seems to point to people who don't change their oil. I've known people who only change their oil once a year, if that. I knew the 1.8T couldn't handle much abuse, but to sludge up with routine 3-5k oil changes using some of the best synthetic oil available?

Please share your friends experience. I would appreciate it.

---

The sludge issues only happened, at the least the vast majority, on the 1.8T engine mounted longitudinally in the Passat and A4. There is a cross member right under the oil pan and for clearance issues the engineers reduced the capacity of the oil pan down to 3.7 qts with the filter. Not enough oil for these cars. The "fix" is to use the larger OEM "B" filter and synthetic oil ... which many of the dealers were not using. Many people had sludge on cars with every service done at the dealer because the dealers were using dino which just could not hold up with that little oil in the pan.

JKH

 

[wavinwayne]

To the original poster,

I have used several different oils, including cheap ST dino, Castrol GTX dino, dealer supplied bulk mystery oil, GC, & M1 0w40 in my '00 GTI 1.8T.

I have never noticed any difference in gas mileage, regardless of which oil I used. I always get 28-29 mpg.