Nope, had some on the shelf and tried that too. I'll know it the updated PCM help this weekend, I'll report back next week.

Tried the vinegar but no go, Soft Scrub did the trick but still need to apply wax, this is gonna be a pain !

When I've got some soot on the transom of my boats I've used Spray Nine and that stuff works like magic. It is wonderful for about any tough boat cleaning job...bilge, vinyl, etc. Just don't get it on threads.

Wipe off as soon as you come out of water

It's when it sits that it gets tough

Running Blue Motor with white transom

I'll post some nasty transom pics tomorrow. Ran today with 5 bottles Techron FI cleaner mixed w/ 65 gallons fuel. Also burning off Merc's winterizing "soup" mix. Transom is nasty!! Same as last year. Once I burn this tank it cleans up for the summer.

and what was your mix ratio - fuel to 2 stroke oil and which oil did you use. Some are bad. I have found a Marine Citgo brand 2 stroke motor oil that has been the best and we have boats that sit for 6 to 9 months min, some even a couple of years stored.

I would not use anything under 50 to 1 ratio mix. Volvo penta has done alot of testing with mix ratio's. they recommend 50 to 1 and IMO for the 496 I would go 60 or 70 to 1, depending on the climate.

Bup, you would be proud. I used your advice and got away from the Merc 10-1 ratio in the fsm. Way too rich IMO. I blended Merc Synblend 2 stroke at 50-1 ratio. Also had the Stabil 360* in with the mix.

Stopped are Wallmart this morning to get supplies for the lake. They had Merc Quick care ethanol treatment on closeout for $5 a bottle. I bought a few. What's your opinion on it? As always thanks for your input and wealth of knowledge.

Just back after a couple of days on the lake with the newly reflashed PCM from MERC, "VERY HAPPY" to report my sooting issue is "NO MORE"....

After 2 days of running through about 70 gallons of fuel, there was hardly any residue on any part of the transom. Before I left for the lake I did give the transom a good waxing just in case it was really needed and I also applied some 303 protectant which was recommended by a friend, made wiping the transom down effortless.

So now I just need to work on why the motor went into an over heat protection mode (195 deg) at the end of our last day out........ , it was a long day making a 10 mile trip at idle back to the ramp, lake was full of debris so I probably sucked something up as I did find some wood debris wedged in the 2 lower water intake side holes. Hoping it's nothing more than a sea pump rebuild, I'll plug in the RINDA DIAGNOSTICS tomorrow and see what it has to say. If anybody has info to share on this over heat, it would be greatly appreciate it.

Happened to me once with one of the HO's in my last boat. It had a mound of wood chips the size of a tennis ball inside the oil cooler on the back of the engine.

My impeller let me down: