Louise

I am scheduled for a oil & filter change next week, 4500 miles @ 12 months. My first oil serrvice was in July, 6 mos. after delivery at 2200 miles. When I talked with my dealer's service department (Laurel Audi in Chicago)they said that while synthetic oil would not harm the engine (1998 2.8) neither they nor Audi recommend synthetics. They use Castrol 10W40. While I would prefer to use a synthetic I am concerned about their remarks. Cam anyone comment? Thanks.<p>LouisE

Erik Addy

opinions on oil are kind of like...<br>well, let's just say everyone has one, OK?<p>But, Audi approves synthetic oil. I can think of several manufactures that go so far as to specificly _recomend_ synthetic, at least in certain conditions (trailering, extremely cold weather, etc.)<p>There really is no question that good synthetics like Mobile 1 are superior to conventional oils, some people just don't think it's worth the expense. Me, I keep my cars longer that the (seemingly) typical 2 or 3 years. Plus, I have modified turbo cars that are pretty hard on oil.<p>Lastly, regular refined 10w40 is NOT an oil I would use in my car. 15w40 is (IMO) a better oil for summer use due to the need for less viscosity modifiers.<p>let me know if you have more specific quesions,<br>Erik

JonC

10W40 nonsynthetic is generally less than optimal because of the high ratio of viscosity enhancers it has compared to a 10W30 or a 15W40.<p>If you're driving only 6,500 miles a year, you might actually benefit from synthetic because it will generally adhere better to engine surfaces during periods of inactivity and will flow better on startup, reducing bearing & other wear on startup (a/the major cause of engine wear). A counterpoint to this might be that if you're changing oil every 3,000 or so, then synthetic is a bit expensive, since it will usually easily last 4-5,000 miles or more (my recent oil analysis on my new A4 at 4,000+ miles showed the oil was still fine -- nonsynthetic factory fill). <p>Yet another option (probably best to wait til out of warranty to avoid claims that the longer interval may void a warranty claim) is to use something like Amsoil, which uses a different base stock and resists acidity better than Mobil 1, so can be left in longer (e.g., 1 year or 6,500 miles).<p>If it was my car, I'd use the synthetic (Mobil 1 10W30 in cold weather, 15W50 in hot) and change every 6 months ( just changed my A4 to Mobil 1 10W30 at 5,000 miles for improved winter cold starting lubrication). Once you're out of warranty you could consider something like Amsoil and change once a year - that's what I'm doing now on my '73 Porsche that gets driven about 2,500 miles a year. Feel free to ask any other questions.

DennisM

I have a 98 1.8t. I drive 1200 miles per week. <br>That makes for an oil change every 4-5 weeks.<br>Could I benefit from Mobil1 by stretching oil<br>changes a couple of thousand miles or would that <br>be pushing the turbo to far, even with synthetics.<br>

John

It may be interesting to note that BMW installs Mobil 1 5W40 exclusively on their E46 cars. (Don't look for it in auto stores--this viscosity only available from BMW who has it specifically formulated for their needs). The recommended oil change interval is approximately 15,000 miles (actual mileage is determined by the cars computer and displayed immediately after starting the car).<p>If you keep a car only as long as the warranty is in effect (on BMW it's 4 years, 50,000 miles) then it makes sense to get the free oil changes only. If you want to keep the car for a few years longer, you may want to add an oil change between the recommended ones.<p>I wouldn't concern myself with the minor increase in per mile cost of synthetic over petroleum based oils--it's a fraction of a cent per mile.<p>Wouldn't consider driving a car in extended sub-zero weather such as we get in Minnesota without synthetic. Protects the engine much better in cold start situations and puts far less strain on the electrical system.<p>Some may argue that such a long interval is imprudent and asking for troubles down the line. But I certainly wouldn't worry about hurting the engine in a turbocharged Audi. The API rating of the oil includes turbo's specifically.<p>My wife's A4 gets Mobile 1 exclusively, primarily because of the cold weather, but as long as any oil meets the minimum API rating specified by the manufacturer, and you change oil at the specified intervals, you are safe under the warranty requirements.<p>It's fairly well established by now that synthetics, in general, are much superior to petroleum based lubricants under virtually any operating conditions, but especially under extreme ones--ie, turbo applications, longer oil change intervals, cold or hot weather, etc.<p>It's really an economic issue whether or not the small additional expense is justified, since your engine should easily get 100,000 miles plus using petroleum based lubricants--unless you live in the frigid north, where the cold start benefits of synthetics make this an easy decision.<p><p>

Darryl W

I use the oil my dealer puts in their Porsches - 10W-40 synthetic, I'm pretty sure it's Valvoline. I have a 1.8 T<p>Darryl<br>98.5 1.8T qms

JonC

My guess is at that time interval you can probably go 7500-10,000 miles between Mobil 1 changes, because the oil isn't in there long enough to pick up much moisture and become acid. You might want to put in some Mobil 1 and then after, say, 5,000 and 10,000 miles, send it in for oil analysis and compare results. THat will help tell you: if it's still good at each interval, 5k and 10k, you can probably go for the longer interval. This depends perhaps on whether you're in dusty conditions, etc. but the oil analysis will detect & report on dirt etc. in oil and help gauge this.

Jon C

There's a lot of discussionon the Mercedes list too about the computer that supposedly monitors oil and tells you when to change. On the one hand you can assume engineers don't want to do anything that will cause premature failure or warranty claims. On the other hand, they also want to build cars that the increasingly typical keep it 3-4 yrs. and dump it leaser will be able to do a minimum of service on... I have extended drain interval a little on synthetics, to anywhere from 5k-7500 miles depending on the use, but I'm wary about relying on the service indicators, and like you, would use only synthetic and change a couple of times a year unless I wanted to spend for oil analysis and ensure that the oil in there's still good.

George Rochford

Porsche started using Shell synthetic 5W-40 oil in all their car in the summer of 93. I believe they switched to Mobil 1 as recently as 1996 or 1997.<p>George<br>97 1.8TqAS TAPII<br>94 911 Carrera 4

tHe uNaBimMeR

5W40 IS available.........Voll Synthese makes it.