M1 10W-30 vs 0W-40 in VW 1.8T motor?

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Jul 6, 2003
Boise, ID
Ok, I used to have it all figured out, but then I stumbled on this webpage, and now I am really confused. I recently purchased a 99 VW passat with the 1.8T motor, with 55K miles. The dealership had changed the oil to penzoil 5W-30. After I bought it, I immediately changed it to Mobil 1 10W-30, as that is what I use in my V-10 Dodge. However, now I am considering switching to the Mobil 1 0w-40, based on what I picked up here. My question is, am I safe to run the 10W-30 out to 5000 miles before changing, or should I dump it now, with about 1500 miles on it? I am concerned about the heat capacity of the 30W vs the 40W in regards to the turbo engine. It does get hot here, over 100 at times. I just completed a 1000 mile trip with the average ambient at 85-90 F, with the 10W-30, and didn't use any. Speeds averaged around 80 mph, with bursts to 100 mph. Any opinions? Tom
Mobil 1 10w30 will do fine in this engine for a 5000 mile interval, but I think going with the 0w40 is a good move. Edit: Just noticed this was your first post, so... [Welcome!] [ July 07, 2003, 10:46 PM: Message edited by: G-Man II ]
I love my 1.8T and I plan to still have it in my driveway when I die in 40 years or so. You can run the 10W30 with no problem, the turbo is water cooled so this engine is not an oil killer unless you really stay in boost all the time. I have gotten good analysis from 5W30 Amsoil on mine but it's hard to fight the urge to go thick. Have you visited ClubB5 yet? If not, just add the .com to it and brace yourself. Joe
Tom, Look in your manual and check what viscosity Audi recommeds for synthetic oil. You could also use the oil finder on the mobil1.com site and try to find what oil your car needs, but I'm pretty sure they won't list an oil for your engine. Like for my Audi engine they will list 0W-40 and 15W-50 as possible substitutes for the (probably) required 5W-40. Many of our VW and Audi engines call for a 5W-40, which is not popular here in the US - although, it is possible to find excellent Pentosynth and Lubro Moly 5W-40.
Id have to say that since the m1 0w-40 isnt available in the 5qt jugs at wal mart for cheap, that I would go with delvac 1, because its slightly better oil, IMO, or the M1 0w-40, because it is an excellent oil, rated better than the 10w-30 in the ACEA and other european tests. 5000 is fine, but realize that you dont really knwo what the P.O. used in the car, so there are no guarantees that the engine is really clean inside. I would consider swapping the oil at 3-4k the first two times, and would also consider using either auto RX or neutra in it for 500-1000 mi. Not that I think the engine will be really dirty, but its at a good point to give it a bit of cleaning, and a good way to ensure that if a sludgy (sp?) oil was used before, even something like a castrol syntec, which may not be as good, that you can be sure your engine is clean and ready to give you top performance for hunderds of thousands of miles. JMH
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