Mercruiser 25W40 Merc 4.3L EFI 53 hours

[Grease is the word]

First UOA on my boat. A 2001 Bryant with Mercruiser 4.3L V6 Vortec with throttle body injection. Total hours on boat is 145. Hours on oil is 53. Duration in crankcase Nov 2003 to July 2004. No makeup oil. Mercruiser oil filter -- a Champion. In use April 2004 to July 2004. ANA Laboratories did the report. Replaced with Amsoil 15W40 Diesel/Marine.

Please see: http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=11;t=000199

for the VOA on this oil.

Sb Titanium Silver Copper 11
Lead 14
Tin 1
Aluminum 3
Nickel Iron 19
Chromium 2
Cd Sodium 4
Boron 129
Silicon 115
Water Soot 0.0
Glycol N
Fuel 6.80
TBN 6.20
Vis @ 100 C Cst. 10.69
Moly 9
Mag 1023
Calcium 431
Barium 15
Phosphorus 1634
Zinc 1781

Lab comments:

Wear Metals - Normal
Lub Contaminants Silicon - Excessive [Critical]
Fuel Dilution, check for leaking injectors - Excessive [Critical]
Drain oil if not drained.
Change filter if not changed.

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My comments: I can understand the high silicon -- boats run with flame arrestors which are just metal plates, basically w/o any air filtration at all. I am going to replace stock flame arrestor with K&N Coast Guard approved flame arrestor that provides filtration and higher flow.

I don't understand the fuel dilution. This thing has a glorified carb -- an EFI that is throttle body injection. The only thing I can guess is that we are always starting and stopping the thing during water sports. When you turn on the ignition, the injectors spray fuel in the intake for starting. Perhaps it is not all getting burned. Fuel consumption is not excessive -- very normal.

Perhaps I should change the oil every 20 hours with cheap Delo.

Certainly not thrilled that the oil thinned to 10.69 -- is that because of the fuel dilution?

One thing I know for sure is that I won't be using this oil again.

Please comment!

 

[friendly_jacek]

Are you sure all that silicon is from dust (boating enviroment should not be that dusty)?
If so, iron does not look bad (i would expect much higher).
Lead and cupper are on the high side, though.
Fuel dilution is bad and bordering harmfull.
I understand that boat engines run extra rich to generate high power at WOT. I guess that also applies to EFI.
Notice that healthy dose of P and Zn in this oil. This is why I think that HDEO is the only decent substitution for 25W40. And one should probably start with high 40 or even 50 oil to allow for that fuel dilution.

 

[Grease is the word]

Thanks for the feedback. I'm not sure the silicon is from dust. What else can cause it?

We don't WOT that much with waterski starts since I am propped pretty low (18P 4-blade), but we do run WOT sometimes to high tail it back to the marina when a storm is coming

.

 

[Geoff]

Interesting. I will post my UOA with same engine but carburated later in the season. I am using M1 15w-50 (and have for years).

The high fuel could be just the fuel map. Mercruiser probably sets them up to run slightly rich. This will often give you better performance at high speed and add a buffer against lean conditions, a very bad thing on a loaded motor.

Also the sparkplugs are (MR43T) are very cold running and get fouled easily. You could have slight misfire.

 

[1 FMF]

hey, posted to your thread over at iboats.

maybe it's all the full throttle starts associated with waterskiing?

 

[joee12]

Bump

 

[BlazerLT]

Possibly your boat needs a full tuneup.

Boat engine run harder than any car application. They never get to cruise or anything, working hard all the way.

Fuel dilution is not an uncommon thing in marine applications.

You should have seen the 460CI big block we had in our 31 foot cruiser.