MMO in gas - RTS 5W40 - 2003 Deville - 5090 Miles

[ronrackley]

This one is to check a run with Shell Rotella T Synthetc ("RTS") 5w40 with no Marvel Mystery Oil ("MMO") used at all - in oil or gas - with one that used MMO in the gas at the recommended dosage of 4 ounces per 10 gallons of gasoline but not in the oil.

The last run, at 75,296 miles on the "unit," was with no MMO at all. The run at 62,525 miles had straight RTS 5w40 oil with no additive, but MMO was used in the gas for it - as was also the case for the other two runs at 57,455 [with Rotella conventional 15w40 having 20% MMO] and 67,898 [with RTS 5w40 having 20% MMO.]

I think that the 3.5 TBN with MMO in the gas vs. the 4.6 TBN with no MMO in the gas is a significant finding.

I still run MMO in my gas, as I have since ethanol became standard in gas by the way.

 

[cchase]

Why are the viscosities all over the place? That alone tells me you can't tell anything about the effect of MMO in this test.

 

[demarpaint]

I was trying to figure that out for myself too.

 

[ronrackley]

Originally Posted By: cchase
Why are the viscosities all over the place? That alone tells me you can't tell anything about the effect of MMO in this test.


The last three runs were all with the same RTS to be directly comparable - the middle one with 20% MMO and the other two without. Looking at all the viscosities, the two without MMO in the oil group consistently higher than the one with 20% MMO in the oil. It seems to make sense to me, if MMO in the oil lowers viscosity a lot and MMO in the gas lowers it a little - although I'm not sure that the differences in viscosity between the ones with and without MMO in the gas are statistically significant. The lower viscosity with MMO in the oil sure looks statistically significant to me.

 

[demarpaint]

The run that caught my eye was 67,898. The oil stayed in grade across the board. Do you think the 5W vs 15W means anything? I'm still trying to learn these things. Looks to me like your engine is doing quiet well no matter what!

 

[cchase]

I don't claim to understand the processes behind MMO in gas well, so that's my disclaimer. When I looked at your numbers, I see that there's a 15-20% difference in 100C KV given. I'd be concerned that with no fuel dilution, enough MMO was getting into the oil at 4 oz per 10 gal of fuel to dilute the oil by 15-20%, especially because the viscosity of MMO is not 0 cSt.

Those were my thoughts, anyway.

 

[demarpaint]

I tried to edit, got side tracked. The 5W vs 15W has no impact at operating temps, we know that. Could that impact this report though? That's what I was trying to ask. I should stay off the phone when I participate in these threads.

 

[ronrackley]

Originally Posted By: cchase
I don't claim to understand the processes behind MMO in gas well, so that's my disclaimer. When I looked at your numbers, I see that there's a 15-20% difference in 100C KV given. I'd be concerned that with no fuel dilution, enough MMO was getting into the oil at 4 oz per 10 gal of fuel to dilute the oil by 15-20%, especially because the viscosity of MMO is not 0 cSt.

Those were my thoughts, anyway.


The difference in the 100C viscosity between the run with MMO in the gas, 14.07 and the run without MMO in the gas, 14.59, is 3.7% and I'm not convinced that it is due to the MMO getting into the oil from the cylinders rather than just being within the margin of error. The large difference in TBN makes it look like something is going on there though, doesn't it? It is known that MMO, when used in oil, both lowers viscosity due to thinning and causes a faster drop in TBN due to acid formation under operation.

The run at 67,898 miles with the much lower 100C viscosity of 12.37 is with 20% MMO in the oil - 1 1.2 quarts of MMO and 6 quarts of RTS 5w40 - and that explains its lower viscosity. Both of the runs I've cited for the MMO-in-gas study had nothing in the engine but RTS 5w40.

 

[chubbs1]

I think things look great, good oil filtration too. The TBN thing could just be an oil issue instead of MMO. I have seen TBN's different with the same oil, same mileage and no MMO. So All maybe you could take from this is the slight thinning of the oil when 20% MMO is added. Engine wear is nice. One thing I would recommend is to do particle counts with your UOA. You could cut the TBN if price is an issue since you know the TBN average for your vehicle.

 

[demarpaint]

I wonder how a qt in his oil vs the 20% would look in the report? I never exceeded a qt even with a 6 qt sump, although I doubt it would make much difference. That engine is doing just fine!

 

[cchase]

Originally Posted By: ronrackley
Originally Posted By: cchase
I don't claim to understand the processes behind MMO in gas well, so that's my disclaimer. When I looked at your numbers, I see that there's a 15-20% difference in 100C KV given. I'd be concerned that with no fuel dilution, enough MMO was getting into the oil at 4 oz per 10 gal of fuel to dilute the oil by 15-20%, especially because the viscosity of MMO is not 0 cSt.

Those were my thoughts, anyway.


The difference in the 100C viscosity between the run with MMO in the gas, 14.07 and the run without MMO in the gas, 14.59, is 3.7% and I'm not convinced that it is due to the MMO getting into the oil from the cylinders rather than just being within the margin of error. The large difference in TBN makes it look like something is going on there though, doesn't it? It is known that MMO, when used in oil, both lowers viscosity due to thinning and causes a faster drop in TBN due to acid formation under operation.

The run at 67,898 miles with the much lower 100C viscosity of 12.37 is with 20% MMO in the oil - 1 1.2 quarts of MMO and 6 quarts of RTS 5w40 - and that explains its lower viscosity. Both of the runs I've cited for the MMO-in-gas study had nothing in the engine but RTS 5w40.


Okay, I see that now. I read the previous run as being MMO in the fuel tank, not in the oil.

No matter what's going on with MMO everything looks good in every report.

EDIT: I still think it's strange, looking at the numbers now MMO appears to have a cnsistently negative impact on TBN.

 

[demarpaint]

If you look through the UOA reports MMO does lower the TBN when added to oil, so that is not much of a surprise to me.

 

[ARCOgraphite]

Is that SAE 40 too thick for that GM engine even in FLA? At thickest I would run 10w-30 rotella triple protect with 1 qt sub of Formula Shell 5w-30.

 

[Capa]

The inconsistency is probably due to Blackstone---their numbers at times are all over the place.

 

[edhackett]

See this thread for a possible explanation of the lower TBN:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2111746&page=1

Ed

 

[Steve S]

Originally Posted By: ARCOgraphite
Is that SAE 40 too thick for that GM engine even in FLA? At thickest I would run 10w-30 rotella triple protect with 1 qt sub of Formula Shell 5w-30.
What would be wrong with the 5w-40?

 

[unDummy]

I don't see anything wrong with ANY of the UOAs here.

Stick with this oil. Whether you want to use the MMO in the fuel or oil, or both, is the choice you have to make.

The visc and TBN with MMO is expected. It will thin the oil a point or so, and its not a TBN booster.

Whether you use it or not, I see no reason that you couldn't go further. Definitely try 7500 miles.

There is nothing wrong with using 5w40 in this engine.

 

[CATERHAM]

Originally Posted By: Steve S
Originally Posted By: ARCOgraphite
Is that SAE 40 too thick for that GM engine even in FLA? At thickest I would run 10w-30 rotella triple protect with 1 qt sub of Formula Shell 5w-30.
What would be wrong with the 5w-40?


Answer. "As thin as possible, as think as necessary"

5W-30 is spec'd for this engine. There is no reason to use anything thicker. The 67,000 plus mile UOA with the lower viscosity is a pretty indicator of that.

 

[FZ1]

No need to stick foreign objects in you oil or gas tank,Hoss.

 

[Santo Fontana]

Do a few more uoas with NO MMO at all and see if anything pops up.

thanks for the uoas!