quote:
Originally posted by moribundman:
I'm latching onto the HT/HS, because that seems to be one of the more important points regarding an oil, at least if you work an engine hard. If I seem obesessed (and obnoxious), rest assured, it's just to beat some more information out of the dead horse, so to speak.
moribundman, you're not obnoxious!
In regard to the importance of HTHS, I will say that it is important that it's at least 3.5 for some or most EU engines. Keep in mind that HTHS limits for ACEA A2 'general purpose oil', A3 'high-performance extended drain oil', and Audi/VW 500/502 oil are all the same.
quote:
I still don't know why while, for example, VW says an oil has to have an HT/HS of at least 3.5 to meet some of their oil specs, it wouldn't matter if that oil actually shears down below the required minimum. Do they just assume an oil that has an HT/HS of 3.5 won't shear down far enough to cause a problem? Can anybody answer that question?
Why does VW/Audi specify 5W-40 in one engine and 0W-30 in another? Because that is what is required. Do these oils guarantee to have the same 40C and 100C viscosity after 7500 miles as they did when new? No. Does this mean we should use a different weight because of this? No. Does the manufacturer just assume an oil that has an HT/HS of 3.5 won't shear down far enough to cause a problem? Yes, as long as you follow the recommended oil spec (A3, SL, 502.00, 229.1), and the recommended normal or severe service interval. If you do not trust the auto or oil manufacturer, use UOA.
quote:
I'm pretty confident that M1 0W-40 is fine in my engine, but I question if it's the best I can get for the price. Sure, Redline sounds good, but the UOAs looked mixed, not to mention I prefer an off the shelf oil that I can easily get. And I'm not willing to pay more than 7 bucks for a quart.
IMO, I would look at your UOA, not other's. Also, I would use an oil that meets the manufacturer's approvals (VW 502/500/501 for your engine). If you don't, in EU, they will not honor your warranty in oil-related claims. They are more serious about oil there.
quote:
That's why I keep looking at M1 15W-50, which, for some reason unknown to me, seems to be shunned by many people here, while it seem to be one of the popular oils with people who have the older 2.8 Audi engine.
M1 15W-50 is the preferred M1 oil weight for [our] 2.8 12V engine. Every VW/Audi mechanic I know agrees with this, because the 2.8 12V has relatively loose cold and/or hot tolerances, large passages, and burns some oil through it's low-tension rings and it's crankcase breather system. Thicker, less volatile oil is good here. Some 12v's have valve clatter at cold startup because of the design of the oil non-return valves under the valley pan, and the pressure relief valves under the valve covers. Some engines are cured with M1 15W-50 and others with 0W-40, depending on individual engine ideosyncrasies, season, etc.
I like M1 15W-50, Pentosynth 5W-40, and LM 5W-40 for my 2.8 12v. M1 0W-40 solved the valve clatter issue, but my engine guzzled it.
[ July 29, 2003, 02:54 AM: Message edited by: geo ]