[77newell]

After 2 years and 5100 miles since the last oil change and the point at which I switched to Rotella T6 full synthetic oil I have sent an oil sample in to Blackstone for analysis. Forest had previously used them so the results ought to be comparable. The numbers for the wear metals were all similar, with my iron results being in the middle of his three sample's numbers. From the records it appears he changed oil annually.

The TBN (Total Base Number), the ability to neutralize acids dropped from 10.6 to 7.9 so there is plenty of reserve left. The viscosity is in the normal range according to Blackstone with minimal if any change.

The iron results are just over a third of amount that Detroit/MTU states as the limiting value for iron in the oil.

My oil consumption has been undetectable. Shortly after the switch to T6 I added 2 quarts but nothing since and the level appears constant.

On the basis of these results I'm planning on keeping the oil for one more year before changing. At this rate the T6 will be cheaper per mile than annually changing the straight 40 weight designated for 2-stroke Detroits and more readily available on the road (though with my consumption that appears irrelevant). One could run the same test as I did, including the TBN, and find that annually changing the straight grade is overkill. The results Forest shared with me hint that that is quite possible, but he didn't get the TBN test.

I hope this helps as we move forward with these quirky 2-strokes.

[HoosierDaddy]

Thank you Jon!! I am very interested in this project!!!

[macgyver]

After 2 years and 5100 miles since the last oil change and the point at which I switched to Rotella T6 full synthetic oil I have sent an oil sample in to Blackstone for analysis. Forest had previously used them so the results ought to be comparable. The numbers for the wear metals were all similar, with my iron results being in the middle of his three sample's numbers. From the records it appears he changed oil annually.

The TBN (Total Base Number), the ability to neutralize acids dropped from 10.6 to 7.9 so there is plenty of reserve left. The viscosity is in the normal range according to Blackstone with minimal if any change.

The iron results are just over a third of amount that Detroit/MTU states as the limiting value for iron in the oil.

My oil consumption has been undetectable. Shortly after the switch to T6 I added 2 quarts but nothing since and the level appears constant.

On the basis of these results I'm planning on keeping the oil for one more year before changing. At this rate the T6 will be cheaper per mile than annually changing the straight 40 weight designated for 2-stroke Detroits and more readily available on the road (though with my consumption that appears irrelevant). One could run the same test as I did, including the TBN, and find that annually changing the straight grade is overkill. The results Forest shared with me hint that that is quite possible, but he didn't get the TBN test.

I hope this helps as we move forward with these quirky 2-strokes.

I had my first oil change when I bought my 87 with the silver 92 ddec, and was quite suprised it took 36 litres . They said the oil should be good for 20,000 miles , I have about 6000 on this oil and plan of leaving it for a lot longer, hopefully that won't cause in problems ? Don

[77newell]

While I can't predict what your oil is capable of, my experience suggests your oil is likely to OK. The only way to know for sure with your particular engine and choice of oil is to take an oil sample and have it analyzed including the extra test for TBN. If TBN gets too low engine corrosion will occur.

Diesel engines tend to have large oil reservoirs, oil changes are not cheap so it makes all the more sense to have the oil analyzed.

[77newell]

After 3 years and 8000 miles I drained the T6 oil and sent in a sample. Over the coarse of the 3 years I did add 6 quarts new oil. Based upon the spot of oil under the engine I suspect most of the oil consumption was leakage. I did recently find the rubber boot on the drive train for the blower was not tight to specification and there was oil residue there.

I have seen no change in oil pressure or consumption with the T6 compared to straight 40wt DD approved oil.

The results from the oil sample are back and the iron barely increased which suggests very low wear. All other elements and properties were just fine including shear viscosity and TBN. Blackstone said they see no problem with letting the oil run another year, but I had already drained it.

Philosophically, I'm comfortable with analyzing specs, making what I consider conservative decisions while gaining the advantages of new technology, and lab testing rigorously. I don't expect everyone to agree with my approach since there is no approval of this from the manufacturer, but as I noted previously there is no way to test this "new" oil, the test engine died and will never be replaced. However, I do need to pay attention because soon there is a new engine oil classification system being implemented and there is no way of knowing how oils might change as a result, or even which oils will remain on the market. I should also note that if someone chooses to have oil sampled and analyzed as I did with the T6 oil they may find that they too could run 3 years and 8000 miles and still have good oil. I would be surprised if indeed that weren't the case.

So what are the advantages of T6 versus straight weight oil? I have proven that I can go 3 years and 8000 miles between oil changes and still have very good oil. I can buy oil off the shelf at most truck stops which I found not to be the case with straight grade oil and so I used valuable storage space carrying oil. The engine cranks faster when cold which makes for quicker starting. I can have all this without increasing my operating costs compared to annual oil changes with straight grade even if T6 cost more per gallon which it doesn't always.

Take this for what it is worth to you, I make absolutely no guarantees that your experience will match mine. I'm just sharing my experience and what it means to me.

[HoosierDaddy]

Excellent Jon! Your findings are very interesting to me. Years ago I brokered for a small "high quality" oil company that catered mostly to agriculture and industrial accounts. This was the kind of testing we frequently were involved in.

[folivier]

Good to see my old coach chugging along.
Nice write up Jon.

[dannymarilyn]

After 3 years and 8000 miles I drained the T6 oil and sent in a sample. Over the coarse of the 3 years I did add 6 quarts new oil. Based upon the spot of oil under the engine I suspect most of the oil consumption was leakage. I did recently find the rubber boot on the drive train for the blower was not tight to specification and there was oil residue there.

I have seen no change in oil pressure or consumption with the T6 compared to straight 40wt DD approved oil.

The results from the oil sample are back and the iron barely increased which suggests very low wear. All other elements and properties were just fine including shear viscosity and TBN. Blackstone said they see no problem with letting the oil run another year, but I had already drained it.

Philosophically, I'm comfortable with analyzing specs, making what I consider conservative decisions while gaining the advantages of new technology, and lab testing rigorously. I don't expect everyone to agree with my approach since there is no approval of this from the manufacturer, but as I noted previously there is no way to test this "new" oil, the test engine died and will never be replaced. However, I do need to pay attention because soon there is a new engine oil classification system being implemented and there is no way of knowing how oils might change as a result, or even which oils will remain on the market. I should also note that if someone chooses to have oil sampled and analyzed as I did with the T6 oil they may find that they too could run 3 years and 8000 miles and still have good oil. I would be surprised if indeed that weren't the case.

So what are the advantages of T6 versus straight weight oil? I have proven that I can go 3 years and 8000 miles between oil changes and still have very good oil. I can buy oil off the shelf at most truck stops which I found not to be the case with straight grade oil and so I used valuable storage space carrying oil. The engine cranks faster when cold which makes for quicker starting. I can have all this without increasing my operating costs compared to annual oil changes with straight grade even if T6 cost more per gallon which it doesn't always.

Take this for what it is worth to you, I make absolutely no guarantees that your experience will match mine. I'm just sharing my experience and what it means to me.

Dear John, How's the oil change working for you? We did had to have United Engines do an inframe overhaul on our 1991 8v92 and now that we are a new starting point, I'm thinking about how to best take care of this rebuilt engine. The #4 cylinder ate one of its exhaust valve seats. After discussion, we decided an overhaul after
32 years was the best course of action. Please advise.

[Richard]

John has been out of the Newell bidness for some years now. He may or may not respond to your request.

[77newell]

Richard is correct, I sold the coach several years ago and am now touring in a self rebuilt interior on a Sprinter chassis.

Based on my aircraft engine experience, if I were in your situation I ptobably would go with straight grade oil until the first oil change and the go to Rotella.