www.iFourWinns.com

The temp stays between 165 to 175 max.

I currently use Mercury Marine and it's 25w40 NOT 20w50 <-my mistake

If it's a Vortec block, the 25w40 should be fine.
Go thicker if it's the older, flat tappet engine.

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2011 Four Winns H180 SS.
Aussie built Mustang 2800.
SOLD - 1997 Four Winns Horizon RS

I had an issue with mine for the first couple of years and kept taking it back for warranty replacement/repair. They finally verified nothing was wrong mechanically and replaced the sender and gauge a few times. The service manager at the dealer told me they had seen some issues with the senders when you have a history of switching between regular and synthetic oil-that it somehow messed with them. Since then I have stuck with the same type of oil and had no issues.

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Paul
2007 Four Winns Horizon 220
Mercruiser 350 Mag MPI w/ Bravo III Drive
2004 Ford Explorer Limited (V8-AWD)
Pomme de Terre Lake (Southwest Missouri)

What oil are you using?

For god sakes man. Did you install a manual gauge as Joet suggested?????

As a licenced tech, that would be the first thing I would do.

We first must separate any engine/oil pressure issues from any electrical/wiring issues.

Goofing around with different oil grades is just plain stupid.

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07 Azure AZ200,
Previous boat,
95 278 Vista,
And a lot of others.

Ontario, Canada

NO! and I'm going to continue asking questions until then.

btw WINTER does SUX !!!!!!!!

the thing is, your main question can't be answered until you do hook up a manual gauge...
my old '88 will usually run from 40-60 when cold, once it warms up idle will be about 20, running 40-50 which is normal for Chevy small blocks.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

And that's the plan. I won't be able to test this out until next weekend so in the meantime I'm just answering questions or gathering useful info by asking away. BTW - I also ordered a 1/8" t pipe to connect the sender and mechanical gauge at the same time. I'll post the results asap!

If you're using the Merc 25/40 oil I can tell you that I get the same readings with that, as I did using monogrades like Chevron Delo 400 straight 30 or even 40. So I don't think the low readings are oil related per se. I switched because the monogrades of Delo 400 are now only diesel rated, not gas rated although the 15w/40 is rated for both. Not sure if it really matters though. I think the Merc oil might give a bit better starting lubrication in cooler temps.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Did you resolve the problem?

I was finally able to head out this weekend and while the dash showed the oil pressure around 0 psi the mechanical gauge didn't go lower than 20 psi.

I'm sorry I didn't see your question way back. I'm using 10W40.

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Paul
2007 Four Winns Horizon 220
Mercruiser 350 Mag MPI w/ Bravo III Drive
2004 Ford Explorer Limited (V8-AWD)
Pomme de Terre Lake (Southwest Missouri)

The VDO gauges are terrible, I have installed mechanical backups to mine in the engine compartment. Funny though while cruising my gauges (VDO) wander all around, I plugged in a small air compressor to the 12v outlet and everything goes haywire when that gets turned on. About the only thing that seems to work consistently is the tach.

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Jon Miller
1998 four Winns Horizon H200
Volvo Penta 4.3 GL
Newtown, CT

untitled-545 by millerjont, on Flickr

I would suggest replacing the wire from the sender to the panel. I have had to do that more than once for customers. Too much resistance in the wire will cause that exact problem.

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Brian Borchik
The Winds of Cold Springs Harbor Marina
Baldwinsville, NY