Penta (GM) 4.3L marine engine; problems - they sent me these test results.

[monster1]

How did you get a sample without MMO in it? I thought you poured the MMO in the sump, which means the whole sump has it.

Unfortunately, Blackstone does not use an accurate method (gas chromatography) for measuring fuel dilution, so you can't really compare this sample to the first one. Blackstone infers fuel dilution from the flashpoint, and is very conservative in their inference. So the same sample tested by BS and a lab that uses gas chromatography will show huge differences, with BS always having the lower result.

I vacuum pumped the sample before I added MMO to the sump. I added the MMO because I was at the bottom mark at the dipstick and wanted to bring the level to full and see if that and MMO made a difference in the noise I was experiencing. Not that I thought MMO is a "magic elixir", just to see if it changed the noise which could possibly indicate that the problem is inside the engine. It did not change the noise issue.

 

[twX]

What was the initial viscosity of this oil?

 

[kschachn]

How did you get a sample without MMO in it? I thought you poured the MMO in the sump, which means the whole sump has it.

Unfortunately, Blackstone does not use an accurate method (gas chromatography) for measuring fuel dilution, so you can't really compare this sample to the first one. Blackstone infers fuel dilution from the flashpoint, and is very conservative in their inference. So the same sample tested by BS and a lab that uses gas chromatography will show huge differences, with BS always having the lower result.

Which has already been explained to him several times and in detail in this same thread.

It’s unfortunate but the money he spent on that UOA was just wasted.

 

[monster1]

What was the initial viscosity of this oil?

Delo 15w-40

 

[monster1]

Which has already been explained to him several times and in detail in this same thread.

It’s unfortunate but the money he spent on that UOA was just wasted.

Yes. I get it. Blackstone doesnt test for fuel dilution the same way. The UOA I took personally, was sent in to Blackstone before I added MMO and before I sent the boat to the shop, which was before they decided to send a UOA to CAT. And all of this was done before I made this post. I guess the 36 bucks I spent with Blackstone just confirms I need to change the oil, run the engine and retest at half change interval. And, based off your information that you apparently think I didn't listen to, will retest with CAT since they are the ones who test properly for fuel dilution.

 

[himemsys]

Yes. I get it. Blackstone doesnt test for fuel dilution the same way. The UOA I took personally, was sent in to Blackstone before I added MMO and before I sent the boat to the shop, which was before they decided to send a UOA to CAT. And all of this was done before I made this post. I guess the 36 bucks I spent with Blackstone just confirms I need to change the oil, run the engine and retest at half change interval. And, based off your information that you apparently think I didn't listen to, will retest with CAT since they are the ones who test properly for fuel dilution.

The way you presented the information prior to this post made it easier to believe what @kschachn was suggesting.

 

[monster1]

The way you presented the information prior to this post made it easier to believe what @kschachn was suggesting.

After rereading my post, I can see where I left people confused and thinking I wasn't listening to anyone and just sending in samples until I got the results I wanted to hear. The story is that my engine was making noise and I sent off a sample to blackstone before I took the boat in for service. The repair shop sent in a sample to CAT without my knowledge and sent me the results. Those results were available within days. Blackstone took several weeks. Based off what I'm told on this post about the fuel dilution issue, I need to retest with CAT at the next oil change. And again, I appreciate everyone's help on this matter.

 

[twX]

Delo 15w-40

That oil starts out at 14.65 cST, and ended up at 11.5 cST, which works out out to around 8% fuel dilution. This assumes no shear-thinning of the oil. A 15W-40 won't shear-thin all that much, so I'm guessing fuel dilution would still be around 5-7%.

So even without the MMO, dilution is probably higher than normal. If you did a lot of cold idling while troubleshooting, that might explain it.

The sodium is probably from salt water, maybe getting in through the air intake or even the fuel system. The elevated wear metals could be from corrosive wear.

 

[monster1]

That oil starts out at 14.65 cST, and ended up at 11.5 cST, which works out out to around 8% fuel dilution. This assumes no shear-thinning of the oil. A 15W-40 won't shear-thin all that much, so I'm guessing fuel dilution would still be around 5-7%.

So even without the MMO, dilution is probably higher than normal. If you did a lot of cold idling while troubleshooting, that might explain it.

The sodium is probably from salt water, maybe getting in through the air intake or even the fuel system. The elevated wear metals could be from corrosive wear.

Thank you for your input. I'll definitely be keeping a close eye on this and use a lab that will do the proper test for fuel dilution.