Diesel conditioner/additive?

[soopad00pa]

I'm picking up a new to me old boat in a week or two and will be motoring much of the way up the ICW (Mid 80s Catalina 30 w/23hp universal diesel), about 225 miles.

I'm changing the oil, filters, and impeller before the trip. Previous owner says it's this season's diesel and he flushed the system before filling the tank.

Is there any kinda magic juice I can/should add to increase the likelihood of a trouble free trip?

[tkeithlu]

Assuming that it really is this last season's diesel, I don't see any need. Adding a stabilizer might help it still be in good shape two years from now, but it can't improve on its current condition.

"Mouse milk." it's a term that came into public use through stock car racing in the 1950s, I think. It refers to magical additives for oil and gasoline that are supposed to, but do not, do more than separate car owners from money. "STP" is the best known.

[CSY Man]

This stuff made a big difference as far as soot on the transom on my boat:
About 75% less soot, great stuff. (I don't have stock in the company)

[soopad00pa]

I'm not surprised to hear it's mostly snake oil.

Maybe I'll try that stuff, if only for psychological armor.

[jamhass]

I'm a fan of diesel biocides.

[Island Time O25]

Originally Posted by CSY Man

This stuff made a big difference as far as soot on the transom on my boat:
About 75% less soot, great stuff. (I don't have stock in the company)

+1 for this stuff.

Also stock up on fuel filters. Lots of fuel filters.

[soopad00pa]

Ok, I'll look for that stuff. I've got a few filters on hand.

So, the manual says Type A transmission fluid, but I haven't been able to find that locally. Any other equivalents? How much does it matter?

[Nord Sal]

Type A ATF is an older designation.


This link might help you to find an equivalent alternative that is currently available.

[soopad00pa]

Thanks. That's a helpful link.

[CaptTom]

A biocide is a good idea. But on a delivery run with old fuel the only difference will be the filters could get plugged with dead bugs instead of live ones.

Bring lots of filters. Check them often, at least at first. After the first couple of refueling stops, any residual growth should be mostly gone. That would be the time to introduce biocide.

[team karst]

Rather in the same position myself. No tank history other than is 17 y/o.

Bought the boat in April, and already gone thru about 4 tanks worth of fuel. Havent touched the filters. Not racors; these have a top panel that gets removed with screws to discover paper pleated, but flatish filter, maybe 2x3 inches.
And, its been thru some seas, 2 meters anyway.
I read so much about diesel issues; so, i really want to visual the tanks from the top. Top is about the only access. And, to do the on-engine filters, which means prefilling and cracking nuts and manual level pumping. Maybe the largest diesel pain points!!

[Lepke]

I've cleaned many infested tanks. Some 20+ years sitting. Biocides usually kill the bugs over days and weeks depending on the brand and mix. They also dissolve solids and sludge over a longer period. Most fuel conditioner makers recommend a 3x dose for problem tanks. Better conditioners also improve the combustion of diesel, so an overdose actually makes old diesel burn fine. I use a conditioner every time I fuel.

I'd add the conditioner before you leave and if possible circulate the fuel thru the filters and back to the tank. You should always carry spare fuel filters. If possible, add a vacuum gauge to the fuel line between the primary and secondary filters. A new filter will read close to zero and I change primaries at 7" of hg.

[rbk]

Originally Posted by CaptTom

A biocide is a good idea. But on a delivery run with old fuel the only difference will be the filters could get plugged with dead bugs instead of live ones.

Bring lots of filters. Check them often, at least at first. After the first couple of refueling stops, any residual growth should be mostly gone. That would be the time to introduce biocide.

^^ X2 Also the possibility of loosening carbon deposits causing issues on a delivery run with high concentrations of additives. If anything open the inspection port (if equipped) and suck out / syphon around the pickup and see if there’s anything (water debris etc) settled at the bottom.