oil pressure issues with 88 160 freedom(3.0)

ric · **Posted:** Thu Aug 18, 2011 12:35 pm

Paul I. wrote:

LouC wrote:

Oil pressure typically varies with engine (coolant) temp. When I first start my engine, the cold slow idle shows about 40 psi, after a few runs on plane, the hot slow idle pressure will be 15-20. A few times I have had issues with a sticking open thermostat. While fishing in the Sound, I will leave the engine idling just in case I have to get going in a hurry (big boat wakes). When the thermo gets sticky, and the engine temp drops from like 165 down to 120 or so, you can actually see the idle oil pressure rise up to 40 again...

Thanks, that I understand and fully agree on. The air temp, I don't, other than the oil should be a little thinner at 90 vs a 70 deg day.

Hot air = hot feet = hot engine bay = hot oil = hot surface water temps = hot water getting picked up = thinner oil = lower oil pressure

At night the water surface temps cool 10-15 degrees and the engine compartment isn't an oven. That lets the oil get thicker and a bit higher oil pressures.

Paul I. · **Posted:** Thu Aug 18, 2011 12:47 pm

I think were I am it is a little cooler in general. The ocean temp here in Boston at night never drops that much!! Air temp might, the ocean maybe 2 or 3 degs.

ric · **Posted:** Thu Aug 18, 2011 12:50 pm

Yeah, the water is brown here. The surface gets super heated, wading in the water is like getting in a hot tub. Even the fish hide in the shade and avoid the sunny spots during the day.

ronan1776 · **Posted:** Thu Aug 18, 2011 1:01 pm

If theses boats had air cooled motors like my Harley I'd say yes air temp is a big deal. Since lake water is so much cooler than the water in our coolant systems in our vehicles, so I'm assuming the oil viscosity would stay up because of a cooler running motor. I'm gonna change to a 40w with a quart of Lucas oil stabilizer and hope for the best.

Paul I. · **Posted:** Fri Aug 19, 2011 8:34 am

I try to use ether a (I am trying to remember the numbers) a 10-40 & 15-50W oil. These engines run REAL hard. No coasting down hill. Always running at 3000+ RPMs.

LouC · **Posted:** Fri Aug 19, 2011 8:45 am

You are really going to be better off using a straight weight, for a couple of reasons. For one, a straight weight does not use the viscosity index improvers that multi vis oils use. They allow the oil to flow better when cold, and not thin out too much when hot. BUT, they don't work great in constant high rpm applications like boats the oil will shear down from use and then you get lower oil pressure. In addition, as they break down the VI improvers can cause deposits in the engine which can cause sticking rings, etc. The wider the span between the lower and higher #, the more VI improver there is used. This is true for conventional, not synthetic oils.
There is a reason why, Volvo specs a syn straight 30 as the preferred oil, and Merc their own 25/40. The Volvo syn 30 will not break down as a conventional oil would. The Merc oil spreads the range a little further, but does not use VI improvers according to them.
For a guy with an older boat, boating in normal temps, (50* and above) just use a straight 40, you should have no cold start problems and your engine will always be well lubricated.

Paul I. · **Posted:** Fri Aug 19, 2011 12:08 pm

Good to know!!! Thanks! I should have said, I do use Mobil 1, over rated, but Target always has it on sale. At times I use Amsoil, both over the past few years have worked for me in the car, truck & boat. Plus, I don't want to give any more money than I have too, to the middle east.

Also, in the car & truck, I change the oil ever 6k miles rather than 4K as the dealers would like. So I save a little between changes.

LouC · **Posted:** Fri Aug 19, 2011 12:28 pm

In my 2 older vehicles (98 Jeep and 98 Subaru) I use Valvoline Maxlife, in the newer one (07 Jeep) I use Mobil 1. All three get changed 3 times a year, usually at less than 4000 miles. The boat gets Chevron Delo 400 straight 40, I change it at winterization in the fall and once in the mid summer if we are using it a lot. My 4 stroke lawn equipment gets straight weight (24 year old mower with a B&S 4 stroke) the newer lawn 4 stroke stuff gets Mobil 1 10W/30.
I also have had great success with Mopar 75w-140 syn gear oil in the diffs in my old Jeep, even though those diffs are pretty light duty, no issues in 13 years and 132000 miles....

ronan1776 · **Posted:** Fri Aug 19, 2011 3:58 pm

Will my boat benefit from a synthetic 40w? I'm here in georgia and summers gets hot as well as the lake temps!

LouC · **Posted:** Fri Aug 19, 2011 4:59 pm

In an old engine, I'd stick with conventional, the syn can clean out all the crud behind the seals, then you can get leaks...
I'd use either Chevron Delo 400, Shell Rotella T, or Pennzoil Marine HD. Anyone of those in a straight 40 would be about the best you can do....

ronan1776 · **Posted:** Fri Aug 19, 2011 5:09 pm

Cool! Thanks for all the advice

ric · **Posted:** Fri Aug 19, 2011 8:58 pm

Tonight on the lake... 23psi idle, 55psi @ 3500.

Not bad for an old boat (2000 h180 3.0) with Rotella T 15w40

ronan1776 · **Posted:** Mon Aug 22, 2011 8:03 pm

Ok here is the skinny! While tryn out my homemade oil drain system I was able to suck all the oil out of the boat with the motor cold. It wasn't milky at all, just thin, black and slippery like normal oil. Tomorrow I'm gonna put delo 40w and a cheap filter and give it a flush, drain again and put delo 40w with either a k&n or mobile filter on there. God only knows what the previous jackwagon, I'm mean owner thought he was doing......any thoughts?

LouC · **Posted:** Mon Aug 22, 2011 9:19 pm

It's better to warm up the engine before changing the oil and filter. I'd just change it and then run it a bit, see of the oil gets dark right away, if not, leave it in, if so maybe you might want to change it again, but I'd probably wait till you winterize it....

ronan1776 · **Posted:** Mon Aug 22, 2011 10:09 pm

I just couldn't believe how thin it was cold. So I sucked it all out. I agree about warming it. So tomorrow I'll add delo, put a filter on it and get all the old crap out. Then put fresh dino and hit the lake......

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oil pressure issues with 88 160 freedom(3.0)

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