Dave M

After reading the former thread, I am starting to consider using Mobil 1 10w-30 instead of 15w-50 here in Dallas in my 1.8t. Here are a couple additional questions and a comment I would like to get feedback on:<p>1) How are the oil viscosity/temperature lines shown in the manual interpreted? I mean, some of the lines have flat ends, which I would think means it is a hard cut-off point. But others have kind of an arrow shape to them that leaves the range open to interpretation. What do these arrows signify?<p>2) Reading the Redline www page on their oils, I found an interesting comment. They do not recommend using their 15w-50 and 20w-50 oils in engines that see engine oil temperatures under 225F. I know the 1.8t's have an oil cooler, and after switching to Mobil 1 15w-50 my oil temp has been running under 225F (around 210F I think, given that the gauge is calibrated accurately). Any comments on this?<p>Anyone familiar with any simliar threads on the quattro list? I tried using the search there, but their search engine only seems to work for the older digests (-1996 and early 1997).<p>Dave M - '97 1.8tm (Mobil 1 ??w-??)

Voice of Reason

Not to single out anyone in particular but just cannot understand why people buy 30,000 dollar cars and expect to squeeze the very last cent of performance out of a 30 dollar oil change. Perspective is what's called for here. Use either synth or regular and change when it's starts to taste a little burnt or acidic! Just kidding - every 3000 is about right for 99% of all drivers. Those who race or tow heavy loads may want to do it more often. <p>...that's all for my little tyrade.

ErikR

The manual, and arrows, are fairly crude guidelines. Some manuals even go as far as citing the ASTM tables, but most are just copies of copies of the old ASTM (and some European certification group: TUV) tables. All the tables are based on a regression of temperature and viscosity.<p>I personally find them meaningless when you use synthetic oil. I mean, how rational is it to compare something like synthetic multigrade to a table with single wt. oil? I'm just old enough to remember single wt. cans.<p>Oil chemistry is pretty complex at this point and well beyond my ability to explain clearly, but for your first point: there is no sharp point of inflection with oil viscosities. So, if you are off by 5 degrees you won't hurt anything.<p>Synthetic 15-50 and up are really for endurance racing and big, hot motors. You know, like a sunbeam tiger that overheats in 10 min. Redline uses a different base chemistry from Mobil, so I'm not sure if they are comparable for the same temps.

Andy Hedin

Personally I think every 3k with synthetic is over-kill...I prefer 5k with Mobil-1...all IMHO

Dave M

1) I already use Mobil 1 synthetic oil.<p>2) Most other auto manufacturers do not have 5 valve per cylinder turbocharged engines.<p>3) Your first sentence makes no sense.<p>4) 3K change intervals are widely debatable.<p>5) None of this pertains to my orignal post.<br>

E

I would stay away from lighter oils, especially if your A4 is<br>"consuming" one quart every 1-2K miles. Your engine <br>will be much happier and cleaner in the long run. Also, the<br>lifters will remained pumped up longer and should clack less at<br>startup.<p>Use a 15/20W-x synthetic oil for your 1.8T in the summer,<br>and a 10/15W-x synthetic in the winter. I would stay away<br>from 0W and 5W oils.<p>I would not change synthetic oil more often than every 5K or<br>7.5K miles. Honestly, high-quality modern engines last a<br>long time regardess of the oil change interval - 3K miles or <br>7.5K miles. Changing oil every 3K miles (for almost all<br>conditions) will not make a difference. If changing your oil every<br>3000 miles makes you happy, go right ahead. I have never<br>experienced or read about any benefits.<p>E<br>86 4KS<br>96 A4QM

Voice of reason

1)Good choice. <p>2)True but each valve developes the same friction forces as a two or four valve setup.<p>3)I'm sorry to hear that.<p>4)By whom? In what regard? Who has ever caused engine damage by changing oil MORE frequently than is recommended by manufacturer?<p>5)It does. You've just got your shorts in a bunch because of an opposing point of view. It's just engine oil not a life or death decision. Do it your way.

CharlieG

As the person who started the latest round of this thread I would like to share my new views on the subject. Although I may agree that if you are "consuming" an excessive quantity of oil and it's not becuase of a leak that a heavier weight may improve things, I do not agree that a blanket recommendation to use 15W/20W-x oil in Summer is advisable for everyone. It appears that based on my conversation with the service advisor at my dealer, Audi is recommending lighter oil weights for general purpose use. In fact, my dealer put 5W-30 in my car knowing that it would most likely be used through the Summer months here on Long Island. I believe but have not verified that there is some sort of TSB (or similar advisory) regarding engine misfires on startup or the complete failure to start that have been traced to the use of heavy motor oils. <p>The manual (IMHO) doesn't help clear things up any either. However, in looking closely at the recommendations/drawings, I suspect that <B>any</B> energy conserving oil will be acceptable over the entire range of operating conditions. The only reason the upward pointing arrow for energy conserving oils ends prior to the one for heavier weight, standard oils is that the box which contains the oil designations simply needs more room in that column. The only siginficant, hard end points are depicted by a flat line. <p>That said, the manual does make reference to prolonged high speed operation at high temperatures when using 5W-30 oil but I don't think they are referring to the energy conserving oils depicted in the graph (again the confusion). <p>As I stated yesterday, for my application I will be using Mobil 1 10W-30 for the Summer and either sticking with that or going to 5W-30 for the Winter.<p>My $0.02,<p>Charlie (98.5 1.8TQMS, 10,100 miles)

E

> becuase of a leak that a heavier weight may improve things<p>I did not say to use heavier oil to improve things, such as reducing consumption. <br>It is a matter of keeping the engine and sensors clean from deposits. Burning<br>that quantity of oil, is bad for the engine. Period. Or else, be prepared to use<br>Techron or Autobahn fuel system cleaner often.<p>> It appears that based on my conversation with the service advisor at my dealer,<br>> Audi is recommending lighter oil weights for general purpose use. In fact, my<br>> dealer put 5W-30 in my car knowing that it would most likely be used<br>> through the Summer months here on Long Island. <p>By default, Audi dealers use 15W-40 dino. I have had discussions with service<br>managers and mechanics at 3 dealerships, and they all have confirmed the<br>importance of using "heavier" oil, for the reasons I have mentioned. I have many<br>years of experience with Audi cars -- their oil consumption and their fast-draining<br>hydraulic lifters. Audi engines tend to favor "heavier" dino or synthetic oils.<br>They are very different from Japanese and US engines.<p>> I believe but have not verified that there is some sort of TSB (or similar advisory)<br>> regarding engine misfires on startup or the complete failure to start that<br>> have been traced to the use of heavy motor oils. <p>If anyone has this, I would like to see it. Thanks.<p>E<p>

ErikR

I agree about the service intervals, but the MANUAL says to use 5w30.