30 weight vs 40 weight in VW 1.8T engines

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I am coming to the conclusion that there is no one best oil or one best weight...it truly does depend on how engine design, construction and materials match up with the makeup of a particular oil. Obviously some oils are indeed "better" "on paper" than others; however, the "best" oil can only be determined by running various oils (with varying weights and chemical compositions) in your engine and seeing how the "marriage" works via UOAs. Also obviously, if the engine maker has done sufficient testing (to include rigorous post-run UOAs) and reports that testing honestly (doesn't "skew" the results for things like CAFE), you should have a good idea what weight will work best.
 

Patman

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Looks close to me on most things, but bearing wear (lead) is greatly improved with 40wts! For that reason, I'd go with the 40wt in those engines for sure.
 
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quote:
Originally posted by SPITMAN: Statistically they all look the same. The only conclusion I draw from this analysis is that the 1.8T is one heck of an engine from a materials perspective. [I dont know]
Spitman, You are probably correct. But to know for sure, we would need the standard deviations so here they are: Wear Xw-30 oils (Xw-40 oils) Alum 0.43 (0.35) Chrom 0.08 (0.09) Iron 1.40 (0.95) Copper 1.01 (1.43) Lead 2.56 (0.37) Tin 0.14 (0.10) #obs. 12 (17) For the Mobil, they are: Wear 5w-30 (0w-40) Alum 0.28 (0.26) Chrom 0.07 (0.09) Iron 1.38 (1.46) Copper 0.80 (0.56) Lead 0.40 (0.24) Tin 0.15 (0.07) As you probably noticed, many of these standard deviations are really high relative to the means which does indeed suggest no statistical difference in means. Just the same, I did some ttests, and the only significance difference I can find was that iron under M1 5w-30 is lower than iron under m1 0w-40. But it is significant only at the 10% level. Then again, getting any significance at all is surprising given the small sample size so there may be something here with the iron.
 
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quote:
Originally posted by Patman: Looks close to me on most things, but bearing wear (lead) is greatly improved with 40wts! For that reason, I'd go with the 40wt in those engines for sure.
Also did the test for lead comparing 30 weights to 40 weights (all samples, not just the mobil 1 samples) and found that 40 weight lead is significantly lower than 30 weight lead only at a 13% significance level. But given the small sample size, this isn't bad so you may be on to something Patman [HAIL 2 U!]
 
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quote:
Originally posted by sbc350gearhead: Pscholte......long time no see. [Cheers!]
Thanks...guess I need to root for the Buckeyes today, huh? [Smile] [Cheers!]
 
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Originally posted by pscholte:
quote:
Originally posted by sbc350gearhead: Pscholte......long time no see. [Cheers!]
Thanks...guess I need to root for the Buckeyes today, huh? [Smile] [Cheers!]

Yes [Cheers!]
 
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quote:
Originally posted by pscholte:
quote:
Originally posted by sbc350gearhead: Pscholte......long time no see. [Cheers!]
Thanks...guess I need to root for the Buckeyes today, huh? [Smile] [Cheers!]

yep! [Big Grin]
 
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So there have been some debates about whether heavior or lighter weight oils are "better". Well, I collected all the UOA reports on VAG 1.8T engines and calculated some summarize stats. All values are for per 1000 miles Wear Xw-30 oils (Xw-40 oils) Alum 0.68 (0.61) Chrom 0.07 (0.08) Iron 2.24 (2.37) Copper 1.34 (1.42) Lead 1.15 (0.48) Tin 0.09 (0.06) #obs. 12 (17) Looks like on average, the 30 weights perform better, at least in this engine. Another raging debate on the VW forums is whether Mobil 1 5w-30 or 0w-40 is better. Well, here is the breakdown: Wear 5w-30 (0w-40) Alum 0.56 (0.51) Chrom 0.07 (0.11) Iron 2.11 (3.11) Copper 1.31 (1.48) Lead 0.42 (0.54) Tin 0.09 (0.05) #obs. 9 (9) Didn't do means tests because of the small sample sizes. But interesting stats nonetheless. [ November 15, 2003, 01:04 PM: Message edited by: VeeDubb ]
 
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VeeDub, People run the M1, 0w-40 instead of their 5w-30 or 10w-30 in VW/Audi engines because they think they're getting better protection, but in fact it's an illusion. The 0w-40 shears dramatically in turbocharged engines, so after 4k-5k miles, it's probably THINNER than the M1,10w-30 in terms of the most important parameter, ie high temp/high shear viscosity. Look at the starting point for both oils: M1, 0w-40 ....3.6 Centipoise M1, 10w-30 ...3.2 centipoise If the M1, 0w-40 shears by even 10%, it no longer any thicker than their 10w-30, which is totally shear stable. This is true even though the low shear rate or "kinematic' viscosity tested @ 100C for the 0w-40 may still be higher, ie in the 12.0-12.5 Cst range .... VW and Audi don't specifically recommend 10w-30/10w-40 for their current crop of engines, but that's tied to saving 0.5% in fuel efficiency with thinner grades. Unless you live in Alaska, a 10w-30 or 10w-40, PAO/Ester based synthetic will provide excellent year round performance. Tooslick Dixie Synthetics
 
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Originally posted by TooSlick: VeeDub, VW and Audi don't specifically recommend 10w-30/10w-40 for their current crop of engines, but that's tied to saving 0.5% in fuel efficiency with thinner grades. Unless you live in Alaska, a 10w-30 or 10w-40, PAO/Ester based synthetic will provide excellent year round performance.
Thanks for your thoughts TooSlick. Couple more questions: 1. I noticed that people tend to favor the 0w-40 because of the VW 50X plus ACEA A3 ratings. How important are these IMO and is it enough to offset the shearing concerns you mentioned? 2. If VW is strictly interested in fuel savings, why would they recommend 5w-40 over 5w-30? Of course, Audi has dropped to 0w-30 now so I see inconsistencies here. I get mixed signals about whether they are trying to protect the engine or protect fuel economy. Do you have any insight about this? Thanks.
 
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The User's Manual for my '01 1.8T New Beetle recommends 5w-40. If not available, they say to use 5w-30. The manual also has a table with various multigrades (including Energy Saving type) to use according to ambient temperature. So, you can really use anything between 0w to 50 if it's within the temp range or accordingly to your UOAs. Like most 1.8T drivers, I've been using Mobil 1 0w-40 since it became readily available but will be switching to Mobil 1 5w-30 and 10w-30 for better shear stability. GC 0w-30 should be good too but it's more expensive than Mobil 1 locally.
 
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VW/Audi want you to use VW 502/505 spec oils if possible, since those are actually tested in their engines. Calling for 5w-40 insures there is a good chance that you will, since those formulations are typically made with European applications in mind. At the very least they will carry the generic ACEA, A3/B3 recommendations. Anything from a 0w-30 to a 10w-40 synthetic works fine in all these engines, provided it's thick enough to meet the VW or ACEA specs .... The first set of data you posted shows that 40wt oils generally provide some improvement in bearing wear, which is to be expected I think. Of course the bulk of the 30wt oils you used to generate your data probably DIDN'T meet the VW 502/505 specs .... Ted
 
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Like most 1.8T drivers, I've been using Mobil 1 0w-40 since it became readily available but will be switching to Mobil 1 5w-30 and 10w-30 for better shear stability.
Hmm, so you'd rather use an oil that doesn't meet the VW-mandated minimum requirements to begin with? There are a few 5W-40 oils available in the US that meet VW 502.00: - Pentosynth 5W-40 - LubroMoly Vollsynthese 5W-40 - Unocal 76 Pure Synthetic Oil 5W-40 I don't think Redline 5W-40 would harm your engine either.
 
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quote:
Originally posted by Patman: Looks close to me on most things, but bearing wear (lead) is greatly improved with 40wts! For that reason, I'd go with the 40wt in those engines for sure.
AMEN! Pretty clear conclusion to me there as well. Lead is one of your major indicators and bearings are the first indicator of an engines health. Fred...: )
 
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quote:
Originally posted by moribundman: Hmm, so you'd rather use an oil that doesn't meet the VW-mandated minimum requirements to begin with? There are a few 5W-40 oils available in the US that meet VW 502.00: - Pentosynth 5W-40 - LubroMoly Vollsynthese 5W-40 - Unocal 76 Pure Synthetic Oil 5W-40 I don't think Redline 5W-40 would harm your engine either.
Mobil 1 0w-40 meets VW 502 but according to some UOAs here, it's not as shear stable as 5w-30. For the rest, I'm aware of them but they're not easily available and more expensive. I rather spend that money on other mods. [Big Grin]
 
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