20 Wt vs 30 Wt Iron Wear Levels from BITOG UOAs

[OldCowboy]

I've posted an analysis of iron wear levels from 245 samples taken from UOAs reported by BITOG members. it can be viewed in the Technical and White Papers Forum.

The major findings of this analysis are:

- 20 weight oils consistently showed lower average iron levels than 30 weight oils. The only time this difference was statistically significant was with Ford and Chrysler V8 engines.

- Mobil 1 oils tend to show higher iron wear levels than some of the other oils in the database. In most cases, the difference is not statistically significant, although there was one case where Pennzoil Platinum showed significantly better iron wear levels than Mobil 1.

- There is adequate data to support the high regard BITOG members have for Pennzoil Platinum oil. In those cases where a direct comparison could be made, Pennzoil Platinum showed reduced iron levels compared to other oils, although these differences were not always statistically significant.

- American designed and manufactured 6 cylinder and 8 cylinder engines tended to show higher iron levels than Japanese and German engines.

 

[d00df00d]

Not bad after a first pass. I hope to be able to go over this in more detail soon.

The one reservation I have right off the bat is that iron numbers on UOAs aren't necessarily correlated with mechanical wear. If all you meant to do is examine differences among the numbers, that's great. I just don't think any conclusions about wear per se are warranted.

Thanks for posting!

 

[hate2work]

Thanks for all the work that went into this.

The only question I have is what does it all mean? I'm struggling to find a conclusion from all this.

 

[addyguy]

Wow. Lot of work went into that - thanks!

 

[modularv8]

Thanks for your hard work/time on this. I have read in research papers that did show higher iron wear in engines operating with lubricants of much higher viscosities (HTHS 150C > 3.5 cP) that were designed for 20 wt (HTHS 150C 2.6 - 2.9cP). Generally "low friction" engines use roller type lash hydraulic lash adjusters and low tension piston rings. It was found that the oil film (of higher viscosity lubricants) between the camshaft and the roller tended the roller to slide rather than roll, leading to higher wear. In another paper, low tension piston rings rely on greater oil film thickness for lubrication between it and the cylinder wall. Higher oil films are correlated with lower viscosity lubricants. And finally, in a paper by Lubrizol, referenced charts of other SAE studies showed an increase in wear of big-end bearings with increasing viscosity (above HTHS @ 150C 2.6 cP). This last one was puzzling to me. I have read in other papers that "thicker" oil leads to increased friction and heat at the main bearings. And as a consequence leads to an unexpected reduction of oil viscosity in the bearing because of the additional generated heat. I expect lots of feedback on this last one.

Different engines produce different wear profiles. However, in your analysis there were averages of wear performed between different engines under the same type of lubricant (ie, Pennzoil Ultra, etc) giving the possible impression that certain lubricant brands/types lead to different wear rates.

I believe the take away from this analysis should be that OEMs design their engines to operate with certain lubricant viscosities and therefore their recommendation.

 

[OldCowboy]

Hi d00df00d,

You are absolutely correct that iron numbers on UOAs aren't the only indicators of wear. To get the best information on motor oils, we would need a full database of API, ILSAC, and ACEA test results. However, I have not seen these results posted anywhere.

Particle counts, PQ Indexes, and filter debris analysis results would certainly give a more complete picture of wear, but are not data commonly available for analysis.

Bottom line: Unless someone can provide another source of data, UOAs are all we've got.

 

[d00df00d]

Originally Posted By: OldCowboy
Hi d00df00d,

You are absolutely correct that iron numbers on UOAs aren't the only indicators of wear. To get the best information on motor oils, we would need a full database of API, ILSAC, and ACEA test results. However, I have not seen these results posted anywhere.

Particle counts, PQ Indexes, and filter debris analysis results would certainly give a more complete picture of wear, but are not data commonly available for analysis.

Bottom line: Unless someone can provide another source of data, UOAs are all we've got.

I agree with all of this, with the *possible* exception of the last line. What do you mean when you say UOAs are "all we've got?" If you meant that as face value, then I guess I agree. If you meant to say it's okay to draw conclusions about wear from UOAs just because there's nothing better, I have to disagree. Most UOAs come from ICP spectroscopy, which easily can show high numbers in a low wear condition or vice versa.

 

[OldCowboy]

Hi d00df00d,

I understand your position. My question is, what other body of data do we have available to BITOG members? I'd love to incorporate it into this analysis.

 

[Pop_Rivit]

Originally Posted By: OldCowboy
Bottom line: Unless someone can provide another source of data, UOAs are all we've got.


As I understand it, UOA's aren't terribly accurate regarding some of the PPM readings. I'm not sure if you could draw any conclusion from the data, other than to stare at it and say "Yup, some are higher and some are lower". It sounds like a lot of work for something of little or no real value or accuracy, especially when the average engine doesn't know or doesn't care about a couple PPM of iron.

Perhaps if you based the analysis on and factored in an expert opinion such as a Dyson analysis that points to a reason for the iron changes, then some conclusions might be drawn.

 

[d00df00d]

Originally Posted By: OldCowboy
Hi d00df00d,

I understand your position. My question is, what other body of data do we have available to BITOG members? I'd love to incorporate it into this analysis.

Well, what exactly is the question you're trying to address?

 

[buster]

Thanks for sharing this.

Modularv8, well said.

 

[OldCowboy]

Hi d00df00d,

There were two questions I wanted to address:

- Do 30 weight oils provide better protection than 20 weight oils?

- Does Mobil 1 show higher iron levels in UOAs than other oils?

 

[d00df00d]

Originally Posted By: OldCowboy
- Do 30 weight oils provide better protection than 20 weight oils?

This is a HUGE question that I don't think can be addressed using the data available on BITOG. It would require quite a body of evidence from various lines of study, and the answer probably would vary depending on the context (engine, conditions, etc.).


Originally Posted By: OldCowboy
- Does Mobil 1 show higher iron levels in UOAs than other oils?

I'd say you covered this one pretty soundly.

 

[OldCowboy]

Originally Posted By: d00df00d
Originally Posted By: OldCowboy
- Do 30 weight oils provide better protection than 20 weight oils?

This is a HUGE question that I don't think can be addressed using the data available on BITOG. It would require quite a body of evidence from various lines of study, and the answer probably would vary depending on the context (engine, conditions, etc.).


I agree fully that this is a HUGE question. However, we now have one body of evidence (UOAs) that indicates that 30 weight oils do NOT provide better protection than 20 weight oils.

 

[d00df00d]

Oh, I see what you're saying.

I would rephrase it a bit, and say that we have one body of evidence that fails to support the idea the xw-30s provide better protection than xw-20s.

 

[hominid7]

Thanks so much for your time and efforts. Interesting reading!