mercrusier oil for HOT temps

[Bror Jace]

"Any name brand 15w40 should fit the bill. No reason to use 20w50 over 15w40 unless your trying to slow consumption. The engine obviously has a large range for oil choices. 15w40 is just so stout and readily available it's hard to ignore."

+1

Any of the major 15W40 oils (Delo, Delvac, Pennz Long-Life, etc.) are real champs in these kinds of applications. Readily available, affordable, shear stable and with an almost-ideal additive package for dealing with moisture and other contaminants getting into the oil.

To be more specific, with marine engines you have a high-moisture environment. Moisture + byproducts of combustion = acids attacking the engine. HDEO oils have the best add-packs to combat this.

20W50 are usually not as shear stable and don't have nearly the add-pack. It won't thin out to a 30 weight or below ... but all that VII that's broken down could form sludge. It certainly isn't helping protect your engine.

I don't know enough about Mercruiser's 25W40 oils. However, I have yet to see a manufacturer-branded oil that impresses ... and I'm talking about any internal combustion engine application on land, in the water or air. You typically get a higher price but mediocre-at-best performance.

 

[Bror Jace]

Tractor & Supply has Shell Rotella 15W-40 at 2.5 gallons for $30. Hard to beat that! Price is good from now until April.

On the same shelf they had Mystick 15W-40 semi-synthetic This whole class of oils (15W-40 HDEOs) is filled with winners.

Just be sure they say SL, SM or SN on the bottle. That means these oils are approved for gasoline engines as well as diesels. There are a few diesel-only HDEOs out there. But, they will be hard to find, especially in mass-market outlets.

What is the creme de la creme of this class of oils? Probably this one:

http://www.schaefferoil.com/supreme-7000-engine-oil.html

Good luck shearing that down with anything short of a jet turbine.

 

[leroyd92]

I have rotella in both my boats and my Harley. Soon to go into my 190cc pressure washer and rotella 1030 in the trucks once its time for change.

 

[leroyd92]

I met a gent yesterday at terribles who had a 98evo with 198xxx on the ticker. Original owner, never taken to a shop, daily rider for the last 16years...

I asked him what oil he used and he said ( tech 2050 )

I said (WalMart supertech ?) he said Yeppp!!! And a filter that fits an R22 motor, usually fram... changed at 2000/3000 since I only have 2QUARTS in the bike.


IM starting to realize the saying (routine maintenance is better then routine neglect )

 

[Clevy]

Originally Posted By: leroyd92
When we say 1540are we talking about diesel rated oil or regular gasser oil?

I ask, because I've seen diesel oils are rated differently.

And you said stout??? Does 1540 have a high shear resistance ???


Yes. Conventional 15w-40 diesel/dual rated oils tend to be very shear resistant. In my shared sump bikes I've ridden over 5000 miles on rotella t 15w-40 before the too end got noisy. Typical mc synthetic 10w-40s get noisy at 2500 or so. The extra noise is due to shear.
Hdeo's are great oils for bikes. I'm using rotella t in my Harley right now.

 

[lars11]

Don't think you have to worry about air temps at all. Boats have unlimited amounts of cooling water and unless something is wrong, you will get your 185-195 temp regardless.
However, under load, local parts in engine may be very hot and there may be some gas contamination of you oil.

What I see in manuals is the following:
Straigt 30 synthetic (Volvo/Merc)
15w50 mineral or synthetic (Volvo)
20w50 (Volvo)
25w40 (merc)

Not common in manuals at least:
Lots of users running HDEO 15w40

Have been running 15w40 Delvac MX for a while now, switching to 20w50 for this summer to test hot pressure.

 

[Donald]

I run Rotella T 15W40. Mercruiser 5.7L

 

[Bror Jace]

Straight 30 synthetic (Volvo/Merc)
15w50 mineral or synthetic (Volvo)
20w50 (Volvo)
25w40 (Merc)

lars11, that's quite the cast of characters you got there. A 30, 40 and two 50 weights (all at operating temp). You might want to start narrowing them down by determining what weight you want once the motor gets warmed up.

A 25w40 should be more shear stable than a 15W40 ... but you might want to look at some UOAs to confirm this ... I thought I heard someone here say the Merc 25w40 is shear prone.

The 20w50 is a marine oil? I wouldn't use a PCMO 20w50 in a marine application. I question it's shear stability as well as it's additive package. How will it handle fuel dilution + moisture?

It's hard to beat one of the many 15w40s available worldwide for shear stability and add-pack.

 

[Ramblejam]

Originally Posted By: Bror Jace
It's hard to beat one of the many 15w40s available worldwide for shear stability and add-pack.


On the "thin as possible, thick as necessary" front: http://www.amsoil.com/shop/by-product/mo...duty-motor-oil/

 

[Bror Jace]

"On the "thin as possible, thick as necessary" front ..."

If that's the way you roll, just about every major blender that puts out a 15W40 HDEO, puts out a companion HDEO in 10W30.

But if you start with a 10W30, and it shears/fuel-dilutes down to a 20 weight, you may experience accelerated wear when pushing the boat hard. Just food for thought ...

 

[lars11]

Bror, the info is from different engines I owned before. I only have a 5.0Gi now and that calls for dino 15w50 or full synth 30(if in the USA..?)
My current fill is a SN 20w50 an I will run it for max 30 hrs. Total time on the engine is 500 hrs.


Originally Posted By: Bror Jace
Straight 30 synthetic (Volvo/Merc)
15w50 mineral or synthetic (Volvo)
20w50 (Volvo)
25w40 (Merc)

lars11, that's quite the cast of characters you got there. A 30, 40 and two 50 weights (all at operating temp). You might want to start narrowing them down by determining what weight you want once the motor gets warmed up.

A 25w40 should be more shear stable than a 15W40 ... but you might want to look at some UOAs to confirm this ... I thought I heard someone here say the Merc 25w40 is shear prone.

The 20w50 is a marine oil? I wouldn't use a PCMO 20w50 in a marine application. I question it's shear stability as well as it's additive package. How will it handle fuel dilution + moisture?

It's hard to beat one of the many 15w40s available worldwide for shear stability and add-pack.

 

[Bror Jace]

"Bror, the info is from different engines I owned before. I only have a 5.0Gi now and that calls for dino 15w50 or full synth 30 (if in the USA..?)

My current fill is a SN 20w50 and I will run it for max 30 hrs. Total time on the engine is 500 hrs."

So the manual assumes the owner will be operating the boat in North America and the oil recommendations reflect this?

There still seems to be some schizophrenia going on here. Once the engine is at temp, do they want the oil to be around 10cSt or 18cSt? The two are very different. Are they assuming the 15w50 (or 20w50) will quickly shear down to something like a thick 30 weight? I think that would take some time ... and or some seriously hard use.

It's recommendations like this that gets some of us to question the wisdom of the manufactures, specifically when they write puzzling maintenance advice in the user manual.

I'm sure your motor will be fine for a season of 20w50, but my previous recommendation remains the same: HDEO 15w40. If you operate frequently in fairly cold conditions, the 5w40 HDEOs may provide better service, specifically easier start-up.

 

[Donald]

Originally Posted By: Bror Jace
"Bror, the info is from different engines I owned before. I only have a 5.0Gi now and that calls for dino 15w50 or full synth 30 (if in the USA..?)

My current fill is a SN 20w50 and I will run it for max 30 hrs. Total time on the engine is 500 hrs."

So the manual assumes the owner will be operating the boat in North America and the oil recommendations reflect this?

There still seems to be some schizophrenia going on here. Once the engine is at temp, do they want the oil to be around 10cSt or 18cSt? The two are very different. Are they assuming the 15w50 (or 20w50) will quickly shear down to something like a thick 30 weight? I think that would take some time ... and or some seriously hard use.

It's recommendations like this that gets some of us to question the wisdom of the manufactures, specifically when they write puzzling maintenance advice in the user manual.

I'm sure your motor will be fine for a season of 20w50, but my previous recommendation remains the same: HDEO 15w40. If you operate frequently in fairly cold conditions, the 5w40 HDEOs may provide better service, specifically easier start-up.


I agree with the 15W40 recommendation. If its not HOT I am not boating.

 

[lars11]

I agree too, I have run 5 seasons on delvac mx 15w40, but that batch is gone now. Thought I would try the 50 weight for a few oci. After all, that's the Penta visc rekommendation.

By the way, one reason for the Penta 50 vs. Merc 40 may be due to that mercs have separate oil coolers, Volvos dont seem to have that.