Group III oils and Turbo

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Aug 15, 2002
One of the reasons I run synthetic is to ensure long turbo life. I'm wondering if group III synthetics are any better than regular dinos at protecting the turbo. I don't do extended drains so Amsoil and Redline are probably not worth it to me. And I'd hate to drive 45 minutes to the Autozone just to get the Mobil 1 0w-40. I can get Castrol Syntec (VW dealer) and Synpower (Napa) in the 5w-40 grade recommended by VW fairly easily. Am I jeopardizing my turbo by using one of these group III's? Thanks again everybody.
IMHO some Grp III oils do hold up better than I's and II's. I cannot say how they do at turbo temps and if they resist coking as well as IV and V's. This one merits further study.
Hi VeeDub, For the past several years, the Saab OE turbo oil has been listed as a "semi" or "blend." Their new OE turbo oil is a full syn (they're now selling both types). Mobil makes Saab's OE full syn, so I'd assume they also make the semi. I think several of the folks here have said that Mobil's semi syn is actually a Grp3 "full" syn. So, relying on a LOT of inference & assumption, I'd say yes, it's OK to use. I don't think it's a great choice, but definitely better than dino. And since you're not looking for extended drains, they should hold up well enough for 5k-6k miles. If either choice is available in an ACEA A3 rating, I'd probably go with that one. Will either protect as well as any of the ACEA A5 rated Mobil 1 xW-30s? I wouldn't think so, but I don't have any comparative info to offer.
Hi-temp oxidation stability is the one area where a GOOD Group III oil can come very close to PAO performance. Keep in mind that not all Group III oils are created equal, and the specs for Group III allow for a significant range as far as impurity levels. Castrol Syntec 5w40 is made by PetroCanada, and they make some of the best Group III. Chevron makes some of the best Group III. And Helix Ultra 5w40 and Rotella T Synthetic 5w40 both use Shell's XHVI, which is an excellent Group III. Any of these oils would do fine in a turbocharged car.
Originally posted by Greg Netzner: I think several of the folks here have said that Mobil's semi syn is actually a Grp3 "full" syn.
I've not seen anyone post this. It's common knowledge that Mobil's only "semi-syn" oil is Drive Clean Blend, and that it is a blend of conventional oil and PAO.
VeeDub, If I wanted an off the shelf oil for a VW turbo, it would be either Mobil 1, 5w-30 or 10w-30. I see NO reason to use their 0w-40 over these other two, given the oil analysis results posted to date. FWIW,I'll probably end up running the Amsoil 0w-30 or 5w-30 in my 225 hp Audi TT turbo on a year round basis. The new Redline 5w-40 also looks to be a very good product, but it's probably a bit more than you want to spend. Some of the SAE papers I've seen show that the Group III based oils don't perform as well in terms of minimizing high temp piston deposits, so I would stick to a PAO/Ester based formulation for any turbo. TooSlick
Thanks for your replies, guys. Great to have experts so easily accessible on this site. Tooslick, You mentioned the 30weight Mobil 1's and I do have a couple questions: 1. What do you think of the 0w-30 Mobil 1. I hear VW is making a move toward 0w-30's and this oil didn't seem to shear down in a recent analysis. 2. Would you recommend that I run a xxW-30 even in the summer with 100 degree weather in a turbo?
Veedub, I'd estimate that over 75% of what I sell for new cars is the Amsoil 0w-30 synthetic down here in Alabama, so I see no problems with this viscosity in general terms. I do think that the Mobil 1, 10w-30 has been showing the best results amoung their 0w-30/5w-30/10w-30, so I'd stick with that for summer use and run the 0w-30 in the colder weather. All things being equal, the thinner oil will circulate more rapidly and do a better job of cooling the turbo bearings .... The use of 0w-30 by VW is mostly to save on fuel, so I wouldn't make too much of it ....You could run anything from a 0w-30 to a 10w-40 synthetic in the 1.8L engine and it would do just fine. I'll probably end up doing that anyway, since the TT is sort of a testbed for me .... Ted
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