Ron AKA

Don't trust Blackstone fuel in oil numbers. They can be grossly inaccurate. Look at hot viscosity (should be >9.3) and TBN (2 minimum).

papa tiger

I would Tarry on the higher number and stick with the lower mileage drain if I run a lot of City/Town miles even if they are expressway ! I kept figures on start ups and see well over 400 average cool/cold engine start ups in oil change intervals. That average will only go way up with the 2.7L system I believe.

SuperCruzin

Is this off the cuff? or do you have evidence to support this statement?

BucketMan

I just don't get the Blackstone thing. Costs $25 for them to tell you if you have to change your oil? That's more than half of what the materials cost, if you're that concerned, just change it!

I understand it can tell you more about your engine due to the metals present in the oil, but are people really tearing their engines apart from an oil analysis?

Just seems silly to me, am I under thinking this?

papa tiger

An oil analysis would be another diagnostic tool if U have a deep in the bowels knock or rattle. A sound that doesn't seem to be crankshaft related possibly balance shaft in nature on some brands.

Ron AKA

It is not off the cuff. There are bunches and bunches of Blackstone Used Oil Analysis reports that report Fuel % as 2% and less, and at the same time a 100 deg. C viscosity of much less than the 30 weight minimum of 9.3. Here is one example at the link below. To get a viscosity of 7.92 as in this UOA would require about 10% or more fuel in the oil. Blackstone is reporting <0.5%. Does not add up.

https://www.f150forum.com/f70/blacks...-boost-231749/

Compare that to this report from Polaris. Their method is more accurate, but cannot measure more than 5%. 4 out of 5 samples test at >5%, while the fifth one is 4.9%. All these samples have much higher 100 deg C viscosity and two are actually in 30 weight spec. These samples probably do have about 5% fuel in them, or perhaps a bit more. Synthetic seems to be more tolerant to fuel.

http://www.bobistheoilguy.com/forums...Number=2914343

SuperCruzin

Thanks.

My first thought was oil shear, but I read that thread just now, and that's interesting.

itguy08

I think you are also focusing too much on fuel dilution and proving Blackstone "wrong"....

There are many ways for oil to loose viscosity:

• Heat
• Shear (from pressure)
• Oxidation (increases with heat)
• Fuel Dilution
• Time

You've got to remember - multi viscosity oils are basically a chemical stew with lots of things to make that 5w30 a 5w30 vs, say a 30.

You have an engine that works hard (no denying that with the EB or any modern engine) with lots of pressure and heat. That makes for a tough job for any oil.

So there could be viscosity changes that are not the result of fuel dilution but the normal breakdown of the chemicals from heat, oxidation, and shear. Especially over 10k miles in a modern engine.

So I guess what I'm saying is don't focus on one "issue" but you have to look at the whole package. It's entirely possible to have low fuel dilution and have an oil that loses viscosity. Conversely it's possible to have a heavily diluted oil loose viscosity.

From what I gather (and I could be wrong) it's hard to accurately measure fuel dilution so there are many different methods. Not sure if one is better than the other but it's just one data point out of many in the puzzle.

Ron AKA

I have no axe to grind with Blackstone. I am just reporting what I see, and considering how they test for fuel dilution (estimating by flash point), and their results, they lack credibility. Sorry, but I am a Mechanical Engineer and go by the numbers. Polaris use gas chromatography, but that method jams out above 5%. However, they tell you that. And GC had much more credibility. If they say 3% it is likely to be very close to 3%.


Yes I agree those other factors could reduce viscosity. But in the space of 5000 km or 3000 miles they should be totally insignificant for good synthetic like Pennzoil. Suggesting they are a factor for that short interval, is just blowing smoke on the issue. Also consider the DI engine produces fine particulates which tend to form sludge and increase viscosity. So if we want to blow smoke on the issue, it can be blown in both directions. But, if one is realistic, fuel dilution is the only one that can have that large of an effect in that short period of time.

latapx

Attached are my oil analysis results from oil changes at 20K, 30K and 40K. A lot of highway miles, but also a lot of hard driving. Overall it looks very good with the exception of the last change where I went almost 11K on the oil change interval.

I'm going to look up the results for this oil virgin at BITOG and post as well.