I hate to make things more difficult for those who have already made up their minds about which engine oil to use, but I *finally* got a response from VW AG about which viscosity grade they recommend for 1.8T's (and 2.7T's).

Summary: VW/Audi now (always?) recommends "any ACEA A3 approved" 5W-40 for "all operating conditions." If 5W-40 is not available, an API SJ approved 5W-30 may be substituted.

This is frustrating since VW/Audi could have just told us all that in the first place, but instead they chose to give us those overly vague and sometimes contradictory charts in the owner's manuals.

Now, in a little more detail, VW/Audi prefers an "ACEA A3 approved" motor oil (apparently) because the A3 specification requires a high-temperature/high-shear (HTHS) viscosity greater than 3.5 centiStokes (cSt), while the A1 specification (similar to our energy conserving spec) requires a HTHS viscosity between 2.9 and 3.5 cSt.

Here's what the ACEA -- essentially the European standards body governing motor oil, kind of like the API here in the States -- has to say about their gasoline engine oil specs A1, A2, and A3:

"A1 Oil intended for use in gasoline engines specifically designed to be capable of using low friction, low viscosity oils with a High Temperature / High Shear Rate Viscosity of 2.9 to 3.5 mPa.s. These oils may be unsuitable for use in some engines. Consult owner manual or handbook if in doubt."

"A2 General purpose oil intended for use in most gasoline engines with normal drain intervals, although it may not be suitable for some high performance engines."

"A3 Stable, stay-in-grade oil intended for use in high performance gasoline engines and / or for extended drain intervals where specified by the engine manufacturer, and / or for year-round use of low viscosity oils, and/or for severe operating conditions as defined by the engine manufacturer."


The VW eingineer who wrote me stated that a 5W-30 oil (ACEA A1 or API SJ energy conserving) could be used under "less severe operating conditions" if ACEA A3 5W-40 was not available, or if one desires better fuel economy. (Sound familliar, new S4 owners?) I find it interesting that he did not recommend 5W-50, 10W-30, 10W-40, or 15W-50 grade oils, and made no mention of synthetic vs. conventional, despite my specificaly asking about synthetics in my e-mail to him.

Now, as for availability, the only synthetic 5W-40 that I could find on the web that specifically mentions its ACEA A3 rating is Valvoline SynPower 5W-40, but there are other synthetic 5W-40's around. I assume that the Castrol Syntec 5W-40 available exclusively from VW/Audi dealers meets the A3 spec, and I have calls into Mobil and Texaco to determine if their Delvac 1 5W-40 and Havoline Synthetic 5W-40, respectively, meet the spec. Delvac and Havoline meet the HTHS spec, at 4.1 and 4.0 cSt, respectively, but I'm waiting to find out if they meet the rest of the specs.

Details on the ACEA specs can be found (in English) at http://www.acea.be/publications.html, under the link "European Oil Sequences 1999."

Now, this may all just be academic, but, hey, I'm from academia, so what would you expect? Not many of us get to see sustained top speed driving on public roads here in the states. And my 1.8T may never see a race track, so I might just stick with Mobil 1 5W-30, and enjoy the extra power, reduced turbo lag, and better fuel economy.

nt

No Havoline motor oil bears any ACEA certification. Perhaps Texaco simply doesn't have its motor oils tested; Havoline isn't listed on the web site as one of Texaco's global products.

Mobil 1 0W-30, 5W-30, and 10W-30 are ACEA A1 certified, and Mobil 1 15W-50 is ACEA A3 certified, but Mobil doesn't offer a 5W-40 in the U.S. They do sell A3 certified Mobil 1 5W-40 in Europe though. That is probably what you can buy from your friendly neighborhood BMW dealer (who will happily charge you $10/quart).

5w40 is a eurospec oil, that is why it is so hard to find in the US (exc. for diesels!). The manual specifies 5w30, and as you point out, 5w30 synthetic is the best of all worlds. Death to the dinosaurs!

I understand that 5W-40 is more common in Europe, but if that is the oil recommended for 1.8T's there, why would the engine want any different here?

I know that 5W-30 is likely more than adequate for the low-speeds encountered in North American driving. The 1.8T also has a large radiator (for the engine's size) and an efficient oil cooler. I have not heard of any 1.8T owner experiencing oil temps above 250 F, even with hard track driving in hot weather. Still, VW AG must have some reason for specifying 5W-40, since 5W-30 is certainly as available in Europe as it is here.

I'd just like an explanation for the inconsistency in owner's manuals, the 5W-40 recommendation for new S4's and European 1.8T's, etc.

I know I'm overanalyzing this, but it's fun (that's what makes us *enthusiasts*), so here goes:

The 5W-40 that Castrol makes for VW/Audi has a kinematic viscosity of 12.8 centiStokes at 100 C, and a poster mentioned that it was primarily designed for the TDI's, which will experience *much* greater load than a 1.8T due to the higher compression ratio (19.5:1 versus 9.5:1). So, under less load, 5W-30, with a viscosity of 10.0 cSt (for Syntec) is probably fine.

The high-temperature/high-shear (HTHS) -- which must be >3.5 cSt for an ACEA A3 oil -- is also probably less important since few people are able to drive 130 mph for extended periods on public highways in the U.S. :( Syntec and Mobil 1 5W-30 have HTHS viscosities of 3.0 and 3.3 cSt, respectively. Close enough, I bet.

I'm just trying to add as much information as possible to the oil debate here, hoping that someone in the future will search the archives rather than posting "What oil to I use?". I've also got lots of info coming to me from Mobil and Valvoline, so when it arrives, I'll probably post that too.

At least until then, I'll still use Mobil 1 5W-30 in my 1.8T, quite confident that I'm well protected.

year. It still bothers me that the manual states that 5W30 can't be used for sustained high speed driving in hot weather. That's why they want us to use a heavier weight like the 5W40.

The A3 certification is what VW recommends; B3 is the equivalent spec for diesels; B4 is specific to direct-injection diesels; and the E-specs are for commercial vehicles, and are summarized below:

E3 This lubricant category provides effective control with respect to piston cleanliness, bore polishing, wear, soot handling and lubricant stability. It is therefore recommended for diesel engines meeting Euro 1 and Euro 2 emission requirements running under severe conditions. It is also suitable for extended oil drain intervals according to the manufacturer's recommendations.

E5 Stable, stay-in-grade oil providing effective control with respect to piston cleanliness and bore polishing. It further provides wear and turbocharger deposit control, soot handling and lubricant stability compared to E3. It is recommended for highly rated diesel engines meeting Euro 1, Euro 2 and Euro 3 emission requirements and running under severe conditions, e.g. extended oil drain intervals according to the manufacturers recommendations.

So it looks as though paranoid VW/Audi owners now have two choices of ACEA A3 rated motor oil -- Valvoline SynPower 5W40 and Mobil Delvac 1 5W40 -- to use in their cars.

Someone posted here a while back saying that 5W-40 Mobil 1, "specially formulated for BMW" was factory fill on all E46 cars.

BTW, is that RTM as in "Read The Manual" or are your initials RTM?