www.iFourWinns.com

Ive used Chevron Delo 15/40 weight in all of my marine 350's. Great robust oil, great price at Wal-Mart, and always good oil pressure.

Ive been using it in my twin 4.3Gi Volvo's and noticed my starboard engine pegs the oil pressure gauge at 80psi when Im getting on plane and when Im cruising its around 60psi. Mt port engine doesnt do this, though but I chalked it up to differences in the sending units (the port engine gauge twitches a little).

Is 15/40 too thick for 4.3l engines? Im going on a big trip tomorrow with the boat. Should I change it out for a 30w?

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1997 Four Winns Vista 278
T - 4.3l EFI
Kohler 4esz Genset
379 hours as of 8/8/21

I really doubt that, because Merc recommends their 25/40, Volvo recommends a syn 10w/40. I bet its the sending unit. I run straight 40 in my 4.3 and the OP tops out at about 65 after a cold start, cold idle is 40, hot idle is about 20.

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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

Dangerous question when asking "What oil should I use" on this board......

My 2 cents. I have run straight 30 wt. oil in my SR with a 4.3L V6 and in our 2000 268 Vista w/5.7L. Never a problem.
Last two boats (twin4.3L V6 and 5.oL V8) ran/run synthetic Mercruiser 25/40 oil as recommended .

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One of 4 Previous (Sold) Boats:
2000 Four Winns 268 Vista

Current Boat: 2004 Chaparral 235 ssi cuddy

Ok cool. I suspect BOTH sending units are slightly skewed. The port side twitches a lot but reads (what I feel to be) normal oil psi. The starboard side always reads really high.

But when hot, both engines settle around 20psi at idle.

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1997 Four Winns Vista 278
T - 4.3l EFI
Kohler 4esz Genset
379 hours as of 8/8/21

Using oil vs. not using oil is highly recommended. Use whatever, having something in there is better then not. As long as it doesn't read 0 you're fine.

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1981 Columbia 8.7
2015 Yamaha FZR - 87mph - sold
2006 Yamaha GP1300R - sold
2003 Chaparral 215 SSI - sold
2009 Stingray 195CS - sold
2000 Four Winns H180 - sold
1976 O'day Daysailer II - sold
Rick's Four Winns H180 Mods/Upgrade Thread

Haha.. I know about the oil questions on this board; over the years Ive seen/participated in some of those threads

Everybody knows the 350 can/will run on anything probably including crisco! lol. So a 4.3 is a 350 with 2 cylinders cut off. No difference, IMO.

Merc recommended 25/40, volvo recommends 30w. Two big differences there but same block. Makes no sense for volvo to recommend a straight weight. I prefer the multi-weight because I boat starting in Michigan April through Michigan late October.

Now that thats out of the 'weigh'...hehe... I just wanted to make sure I wasnt going to rupture an oil filter casing or blow a gasket or something. That would not be good, especially since Im venturing out onto the great Lake Huron this weekend.

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1997 Four Winns Vista 278
T - 4.3l EFI
Kohler 4esz Genset
379 hours as of 8/8/21

They do? I havent seen that anywhere. Last night I pulled out my "owners manual" that looks like it was printed in 1970 from Four Winns and it said single weight (30w preferred) ONLY. It clearly stated not to use a multi-weight.

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1997 Four Winns Vista 278
T - 4.3l EFI
Kohler 4esz Genset
379 hours as of 8/8/21

This happened in September 2011. Your engines do not need or use synthetic. Use SAE 30 in your engines because that is what they were designed for.

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One of 4 Previous (Sold) Boats:
2000 Four Winns 268 Vista

Current Boat: 2004 Chaparral 235 ssi cuddy

Ah ha! Thanks for posting that.

I dont use synthetic, used to, and quickly realized it was a waste (in my boat motors at least).

Although I dont use a 10w-40, Im sure the 15w-40 I put in there is fine, based off Volvos change in their oil recommendation.

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1997 Four Winns Vista 278
T - 4.3l EFI
Kohler 4esz Genset
379 hours as of 8/8/21

Yes, you should be fine for your trip and balance of the season.

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One of 4 Previous (Sold) Boats:
2000 Four Winns 268 Vista

Current Boat: 2004 Chaparral 235 ssi cuddy

As long as we are talking about oil, what is the opinion about adding a little SeaFoam to the oil ?? I have done that for years in my 2003 Expedition with 180,000 miles on it, and seems to work just fine.....

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1994 235 Sundowner w/351 Ford

Straight 30W oil ? unheard of in the UK for car engines since the 1950's ! I found a local farm supplier, he said he can get some if I really wanted it ( and more expensive than synthetic oil as it's rare !) but it's only recommended for some old tractors and lawnmowers ! I use 20w/ 50 synthetic with no issues ! I've also used some 10w/ 40, it made no difference to the oil pressure

15W50 fully synthetic in mine. Sounds to me like your pressure sender is bad...

Only other remote possible cause is the oil filter is full of crap and the bypass valve on the oil pump is not working correctly - but that's a really big reach. The lubrication system on Chev small blocks is incredibly good and amazingly efficient and after racing them for 20+ years I can tell you lubrication problems are almost unheard of.

Maybe swap the sends between the motors and see if the problem moves. If not the sender, then maybe the gauge.

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Alec

2006 Horizon 190
VP 4.3GL/SX, Sunsport

Volvo recommends straight 30 wt in that engine, regular, not synthetic.

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

This.

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One of 4 Previous (Sold) Boats:
2000 Four Winns 268 Vista

Current Boat: 2004 Chaparral 235 ssi cuddy