Usually marine engines are run at lower coolant temps that enable the highest power output and richest air fuel ratios for the highest power and running under load. The tuning would be like a gasoline bobtail truck . Tunes for a heavy load operation.
What oil in 496 cid 375 HP Mercrusier
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I know the 2.8l crd italy built engine used in the jeep kj (liberty), requires a 0w-40 (mobile 1 euro blend only). I have a cousin that pulls up to 5,500 pounds everyday with hers. 5,000 mile oci and it has held up for 175,000 miles, she has recently switched to m1 5w-40 because of availablity.
Originally Posted By: Chris142
Originally Posted By: PT1
Marine engines get:
1. serious fuel dilution
I'm boat dumb. Why more fuel dilution than any other engine?
Mine are 454 7.4L GM blocks with multi port fuel injection and forged pistons, cranks, rods & cams. They run at 165F tops and get 380HP each with over 500 Ft Lbs torque. When you start them cold they rattle like a metal bucket full of rocks until the internal components heat and expand to tolerance. Then they are quiet and smooth as can be. All this time the EFI is tuned rich to get them to fire on the first touch of the starter (which they do) so you get lots of fuel blow by. You don't get fuel burn off running at 165F until you have been cruising for about an hour at 3200-3600rpm so the oil MUST have resistance to dilution.
Secondly, Mercury Marine uses the Delphi ECM (same one that is used in the Harley TC engines) which when under acceleration load in a 16,000 lb. boat retards back the timing on average 6-8 degrees to prevent detonation then automatically adds back the timing as you pick up speed. This is also another rich condition that can promote fuel blow by.
SO a Marine or Racing oil made for heavy fuel dilution is recommended.
Originally Posted By: PT1
Marine engines get:
1. serious fuel dilution
I'm boat dumb. Why more fuel dilution than any other engine?
Mine are 454 7.4L GM blocks with multi port fuel injection and forged pistons, cranks, rods & cams. They run at 165F tops and get 380HP each with over 500 Ft Lbs torque. When you start them cold they rattle like a metal bucket full of rocks until the internal components heat and expand to tolerance. Then they are quiet and smooth as can be. All this time the EFI is tuned rich to get them to fire on the first touch of the starter (which they do) so you get lots of fuel blow by. You don't get fuel burn off running at 165F until you have been cruising for about an hour at 3200-3600rpm so the oil MUST have resistance to dilution.
Secondly, Mercury Marine uses the Delphi ECM (same one that is used in the Harley TC engines) which when under acceleration load in a 16,000 lb. boat retards back the timing on average 6-8 degrees to prevent detonation then automatically adds back the timing as you pick up speed. This is also another rich condition that can promote fuel blow by.
SO a Marine or Racing oil made for heavy fuel dilution is recommended.
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Marine use is brutal on an engine.
Ok I understand now. I'd think a Straight SAE40 or even 50 would be a good choice in those conditions.
Yes and no viscosity improvers.
Originally Posted By: Chris142
Ok I understand now. I'd think a Straight SAE40 or even 50 would be a good choice in those conditions.
You don't necessarily have to go to a straight weight 50. In most instances an HDEO straight 30 works very well under just about all conditions. The better 15w-40 HDEOs have also established themselves in mainstream marine use. A multivis can make starting at the edges of the season a little easier, particularly if you boat further north.
The main point of this is that high tech "0w" and high vis spread PCMOs, regardless of pedigree, will not do as well in a marine engine. Even super HDEOs like RTS and D1 give me pause in a marine environment. It's a CHEMISTRY issue.
Ok I understand now. I'd think a Straight SAE40 or even 50 would be a good choice in those conditions.
You don't necessarily have to go to a straight weight 50. In most instances an HDEO straight 30 works very well under just about all conditions. The better 15w-40 HDEOs have also established themselves in mainstream marine use. A multivis can make starting at the edges of the season a little easier, particularly if you boat further north.
The main point of this is that high tech "0w" and high vis spread PCMOs, regardless of pedigree, will not do as well in a marine engine. Even super HDEOs like RTS and D1 give me pause in a marine environment. It's a CHEMISTRY issue.
"I'd think a Straight SAE40 or even 50 would be a good choice in those conditions."
I still think straight 50 and (especially) 20W-50 is over used in high-horsepower applications.
A couple of years ago I was talking to a local guy who raced boats years ago on Lake George in New York. I forget the crazy-horsepower figures he cited everyone was running at the time. The only oil he ran was a straight 30. Now, he didn't seem very knowledgeable about oil ... but I have to think there's at least a grain of wisdom embedded in his experience. 30 might be fine for even some seriously high-horsepower applications before any fuel dilution. So, if you race and change the oil every weekend, this might be an option.
PT1 above cited running temps of "165°F tops" ... and I totally take him at his word.
But if you go to Red Line Oil, they will tell you the following about their 'regular' 20W-50:
”Not recommended for street use in production engines that see sustained oil temperatures below 225°F (those engines should use Red Line 10W-30 or 10W-40)."
So, their 50 weight oil is for sustained temps above 225°F. That's a lot hotter than 165°F.
Assuming these 454s used in marine applications are not assembled intentionally very loose for some reason, I'd think the ideal weight is something closer to a 40 weight. A 50 weight oil will make the engine work harder as it overcomes oil hydrodynamic drag in addition to it's primary job of overcoming driveline load.
Red Line might not be factoring in fuel dilution in their recommendation above ... although many race and high-performance engines run very, very rich so maybe they are.
I still think straight 50 and (especially) 20W-50 is over used in high-horsepower applications.
A couple of years ago I was talking to a local guy who raced boats years ago on Lake George in New York. I forget the crazy-horsepower figures he cited everyone was running at the time. The only oil he ran was a straight 30. Now, he didn't seem very knowledgeable about oil ... but I have to think there's at least a grain of wisdom embedded in his experience. 30 might be fine for even some seriously high-horsepower applications before any fuel dilution. So, if you race and change the oil every weekend, this might be an option.
PT1 above cited running temps of "165°F tops" ... and I totally take him at his word.
But if you go to Red Line Oil, they will tell you the following about their 'regular' 20W-50:
”Not recommended for street use in production engines that see sustained oil temperatures below 225°F (those engines should use Red Line 10W-30 or 10W-40)."
So, their 50 weight oil is for sustained temps above 225°F. That's a lot hotter than 165°F.
Assuming these 454s used in marine applications are not assembled intentionally very loose for some reason, I'd think the ideal weight is something closer to a 40 weight. A 50 weight oil will make the engine work harder as it overcomes oil hydrodynamic drag in addition to it's primary job of overcoming driveline load.
Red Line might not be factoring in fuel dilution in their recommendation above ... although many race and high-performance engines run very, very rich so maybe they are.
There are several reasons marine engines might need a higher viscosity oil:
Sustained heavy loads/high throttle openings in cruisers and sport boats
Fuel dilution
As noted, low coolant temps from an unlimited supply of cooling water, and low temperature thermostats (often 145-160 degrees) reduce the need for high viscosity oils.
So there are reason for and against boats requiring heavy oils. Most of the pleasure boats I observe in use don't have heavy duty usage.
Sustained heavy loads/high throttle openings in cruisers and sport boats
Fuel dilution
As noted, low coolant temps from an unlimited supply of cooling water, and low temperature thermostats (often 145-160 degrees) reduce the need for high viscosity oils.
So there are reason for and against boats requiring heavy oils. Most of the pleasure boats I observe in use don't have heavy duty usage.
A straight 30 wt oil should in theory protect better that a multi visc oil 10w-30, for example all things equal as possible. The coolant/water temps in the engine may not mean the oil temps are the same. when I had my boat the oil pressure would be around 80 psi cold then drop to 50 psi hot this was with a flat bottom drag style boat cruising around you couldn't hold it wot for very long. With a real boat or an off shore type you can hold wot pretty much untill you run out of nerves and that is quite a load on the engine/s etc. which means the oil can get hot, there are some pretty big oil coolers for boat engines. When I had a boat Which was from 19 years old to 51 years old I would setup my engines with stock bearing clearances and piston and ring clearances recommended by the mfgs. I miss having a boat to mess with I am getting out of mechanical joys I sold my boat and ATVs no motorcycles sports cars etc. Only appliance like vehicles.
I would run 15w-40 HDEO is my engines or 20w/50. The HDEO would keep the engine cleaner than the 20w-50 though. DUH.
FYI, went marine oil shopping for my tub this weekend. West Marine had the Quicksilver 25w40 for 19.99/gal and Delo400 40w for 17.99/gal and Pennzoil Marine 40w for 18.99/gal.
I stuck with my 25w40 that has worked so well for over 20 years. The syn blend 25w40 was 24.99/gal. But I stuck with the dino.
BTW, WalMart had Quicksilver for $5.87/qt and Pennzoil Marine 40w for $4.87/qt. So the gallon jugs at West Marine are a better deal. So much for the WalMart roll back [censored].
I stuck with my 25w40 that has worked so well for over 20 years. The syn blend 25w40 was 24.99/gal. But I stuck with the dino.
BTW, WalMart had Quicksilver for $5.87/qt and Pennzoil Marine 40w for $4.87/qt. So the gallon jugs at West Marine are a better deal. So much for the WalMart roll back [censored].
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Originally Posted By: PT1
West Marine had the Quicksilver 25w40 for 19.99/gal and Delo400 40w for 17.99/gal and Pennzoil Marine 40w for 18.99/gal.
BTW, WalMart had Quicksilver for $5.87/qt and Pennzoil Marine 40w for $4.87/qt.
I was going to come on here and recommend the Quicksilver 25w40 and Pennzoil Marine 40W also. They are great oils. Also, I've seen them both at my local Wal-Mart for those that don't have a marine center local.
West Marine had the Quicksilver 25w40 for 19.99/gal and Delo400 40w for 17.99/gal and Pennzoil Marine 40w for 18.99/gal.
BTW, WalMart had Quicksilver for $5.87/qt and Pennzoil Marine 40w for $4.87/qt.
I was going to come on here and recommend the Quicksilver 25w40 and Pennzoil Marine 40W also. They are great oils. Also, I've seen them both at my local Wal-Mart for those that don't have a marine center local.
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