Long OCI's and Wear Numbers

[Merkava_4]

Several members have been recommending long 10,000 mile OCI's with full synthetic oils such as Mobil 1 in threads such as this one.

Would running two 5000 mile OCI's back to back as opposed to one long 10,000 OCI yield lower wear numbers overall?

Once wear metals start floating around in the oil, do those wear metals cause even more wear metals? AKA snowball effect ?

 

[Triple_Se7en]

Always get a used oil analysis with long OCIs.

Personally, I use synthetics & never go beyond 6K. I just feel better doing it this way - even if Blackstone tells me it's OK to go longer.

 

[cfromc]

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Would running two 5000 mile OCI's back to back as opposed to one long 10,000 OCI yield lower wear numbers overall?

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Way too many factors to easily answer that but if using the same oil, filter, and same vehicle, I'd actually go out on a limb and say that the 2 5K OCIs added together would either have the same amount of wear metals or more than 1 10K IF you use a good oil and filter and don't have an intake air leak, coolant ingestion, or some other mechanical problem.

 

[coffee]

I simply prefer 5k OCI's with any type of oil as it safely protects the engine and doesn't risk pushing it too far.

 

[kgb007stb]

look here good stuff:
http://theoildrop.server101.com/forums/s...0&fpart=all

 

[Merkava_4]

RI_RS4

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Might I also say that since the engine oil dilutes the wear metals, that engine oil capacity also impacts the measured results. A 10L capacity, as shown in the previous post, is unusual. Most automotive engines are in the 4 to 5L range.

Given exactly the same engine, with exactly the same wear patterns, a change in the sump capacity of 2:1 will decrease the measured wear by 2:1, also.

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I totally agree with that post; increasing the sump capacity will surely decrease the wear metals given the same OCI. Big freightliners running 30,000 mile OCI's have a sump capacity of about 42 quarts.

 

[cfromc]

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RI_RS4

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Might I also say that since the engine oil dilutes the wear metals, that engine oil capacity also impacts the measured results. A 10L capacity, as shown in the previous post, is unusual. Most automotive engines are in the 4 to 5L range.

Given exactly the same engine, with exactly the same wear patterns, a change in the sump capacity of 2:1 will decrease the measured wear by 2:1, also.

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I totally agree with that post; increasing the sump capacity will surely decrease the wear metals given the same OCI. Big freightliners running 30,000 mile OCI's have a sump capacity of about 42 quarts.

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I think you read that wrong; it states that the increased sump capacity impacts the "measured results", not that the increased capacity reduces wear metals. I doubt if increasing the sump volume has a directly proportional affect of decreasing the wear metals, it just causes them to be more diluted. 100ppm in a 5qt system becomes 50ppm in a 10qt system and so on. The wear metals have not decreased however. Perhaps because of other indirect affects, the wear metals will be less due to an increased sump capacity, i.e. additives don't deplete as quickly, lower oil temps, more shear stability, or whatever, but to make the statement that increasing the sump capacity will surely reduce wear metals, well, it sounds reasonable, but I haven't seen anything proving that when talking about a passenger car or light duty truck.

 

[Merkava_4]

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RI_RS4

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Might I also say that since the engine oil dilutes the wear metals, that engine oil capacity also impacts the measured results. A 10L capacity, as shown in the previous post, is unusual. Most automotive engines are in the 4 to 5L range.

Given exactly the same engine, with exactly the same wear patterns, a change in the sump capacity of 2:1 will decrease the measured wear by 2:1, also.

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I totally agree with that post; increasing the sump capacity will surely decrease the wear metals given the same OCI. Big freightliners running 30,000 mile OCI's have a sump capacity of about 42 quarts.

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I think you read that wrong; it states that the increased sump capacity impacts the "measured results", not that the increased capacity reduces wear metals. I doubt if increasing the sump volume has a directly proportional affect of decreasing the wear metals, it just causes them to be more diluted. 100ppm in a 5qt system becomes 50ppm in a 10qt system and so on. The wear metals have not decreased however. Perhaps because of other indirect affects, the wear metals will be less due to an increased sump capacity, i.e. additives don't deplete as quickly, lower oil temps, more shear stability, or whatever, but to make the statement that increasing the sump capacity will surely reduce wear metals, well, it sounds reasonable, but I haven't seen anything proving that when talking about a passenger car or light duty truck.

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I guess what I'm thinking is that since there is MORE oil in the sump, than the amount of dirt per square inch would be less; there by contributing to less wear. Does that make sense?

 

[Curious Kid]

Less concentration as far as wear particles, etc. So on that note, w/o any change in oil flow rates , yes it might appear possible to have a decreasing wear rate (per unit of time), if indeed such wear is induced by wear particles that remain in suspension of the bulk oil. This would lead me to question the quality of filtration and/or ability of such a viscosity of oil in us to protect, if machined clearance and surface finishes aren't limiting factors already.

Take care.

 

[Gene K]

You also get increased wear from fresh oil. There are several SAE papers on this.

I think the best way to handle your concern with the least amount of wear is a Bypass Filter.

 

[cfromc]

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You also get increased wear from fresh oil. There are several SAE papers on this.

I think the best way to handle your concern with the least amount of wear is a Bypass Filter.

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In regards to your first statement; I agree and that's yet another reason to run extended drains. In regards to your second statement, I'd say it depends on the situation. I doubt if a bypass would hurt on any vehicle but I also question if its needed on most vehicles. For diesel engines and some gas V8s that run extended OCIs, i.e. over 20K, I believe the bypass may help but for most gasoline engines and engines that run <15K OCIs, I'm just not convinced that the bypass systems are worth the extra expense.

 

[Merkava_4]

I appreciate all your comments gentlemen, but would anyone care to take a stab at the original question?

Would running two 5000 mile OCI's back to back as opposed to one long 10,000 OCI yield lower wear numbers overall?

 

[Greggy_D]

This CANNOT be answered with a blanket YES or NO. There are too many variables: oil used, oil weight, engine, driving style, environment, climate, etc.

 

[Lexura]

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I appreciate all your comments gentlemen, but would anyone care to take a stab at the original question?

Would running two 5000 mile OCI's back to back as opposed to one long 10,000 OCI yield lower wear numbers overall?

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Did you read this link, esp about this part? If you are really committed to find the answer, why not ordering the SAE paper indicated below?
http://neptune.spacebears.com/cars/stories/mobil1.html

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Engine wear actually decreases as oil ages. This has also been substantiated in testing conducted by Ford Motor Co. and ConocoPhillips, and reported in SAE Technical Paper 2003-01-3119. What this means is that compulsive oil changers are actually causing more engine wear than the people who let their engine's oil get some age on it.

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[Merkava_4]

Lexura,

I read the entire link you posted about the Mobil 1 test of 18,000 miles on the 2002 Chevrolet Camaro. I'm still trying to wrap my brain around the concept of such long intervals on synthetic oil; I don't know if I can ever get my brain past 7500 miles on full synthetic, but I'm trying.

I gather the general consensus is that a 10,000 mile OCI with a filter change at 5000 miles is better than two complete separate 5000 mile OCI's then huh?

 

[ThirdeYe]

Wow I didn't know that you cause more wear by changing it more often, you'd think fresh oil would be good for a car...

 

[Merkava_4]

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Wow I didn't know that you cause more wear by changing it more often, you'd think fresh oil would be good for a car...

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Yeah, I'm having an EXTRA hard time wrapping my brain around that one.

 

[toocrazy2yoo]

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Wow I didn't know that you cause more wear by changing it more often, you'd think fresh oil would be good for a car...

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Yeah, I'm having an EXTRA hard time wrapping my brain around that one.

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It's been common knowledge, or at least AVAILABLE knowledge, based on UOA for a long time. This wasn't the first one of these accounts I've seen, even before I started reading here a few years back. I ignored it and continued my 3 and 4K OCI on Mobil 1 back then, but no more. For some time I've been a believer, owing as much to reading the research elsewhere as here, that long OCI is the way to go with a synthetic. The TBN, the wear metals all these things are more favorable later in the OCI, much later, at least to the point that the oil moves out of grade. Note the 12K filter interval also. So they replace the oil filter, top it off (the top-offs in all these extended OCI examinations were critical), lo and behold, the metals dropped and didn't reach early OCI levels until nearly 18K.

Caveats? Sure, plenty. I wouldn't stretch these GroupIII syns like that, and if Mobil 1 is now in that category you wouldn't want to test the 18K limit. These guys did this test with PAO M-1, or I assume so, the copyrights go back on this thing to 2002. So, although ExxonMobil gets all evasive and wormy about giving us an answer as to present-day composition of M1, we can assume 4 or 5 years back it was PAO. In favor of the longer interval however, the depicted 18K OCI was done in fairly high-HP LS1 V-8s, a much more stressful environment than the average 4 or 6-banger rollerized DOHC eco-car with 4-valve cylinder heads.

I'm very tempted, with 7400 miles on my pre-November 2005 PP and PureOne with 2 OCI and about 14K on it, to just change the filter (haven't had to top off yet) and add the make-up oil and take it to 12K and let Terry analyze it. The way I'm running up the miles, it will only be another 2 months, tops. I fact, as I sit and tap this little missive out, I believe I'll do just that. I will, however, cut open the PureOne that's on the car now with and post the pix. Hopefully, I can get the BlackStone folks to send me a new kit as I burned my last one sending out the "new" Havoline sample. I'll post the results, for whatever they're worth. Gotta remember, I'm running a 105HP 1.6 2005 Hyundai Beta 4-cylinder with DOHC and only just shy of 40K. Hardly a stressful environment, but certainly representative of many, many vehicles here that are needlessly getting 3K OCI, but perhaps there will be meaning.

 

[Pablo]

There really is no snowball effect.

In a clean running engine with proper filtration in good mechanical shape, a 10K OCI will produce less overall wear than 2 5K OCI's.

The reasons are due to the necessity to activate the additive package for best wear protection, the junk introduced due to the change process (stuff in new oil and new oil filter, open filler cap, etc) and the dry start.

While I don't find the spacebear oil study a good example (I think that GM engine had issues) - there are plenty of folks doing 10K+ oil changes with no issues. My two Volvos rarely get the oil changed under 10K, one with 270K miles, the other now at 110,000 (that one had a 20K OCI).....pretty soon I'll be doing 12K OCI's on the Odyssey with zero worries.

 

[cfromc]

I'm curious why some people are recommending a filter change half-way? Unless a $1 junk-filter is used I see no reason to change it more often than the oil is changed on a passenger car/LT.