Thinking of switching from Merc 25w40 to 15w40 HDE

[Volvohead]

Originally Posted By: Bror Jace
Trying to figure out a proper oil change interval?

Think of converting hours to miles thusly:

If you run a boat hard, is that comparable to running a car at 100mph? Then 1 hour would be equivalent to 100 miles.

50 hours would be equivalent to a 5,000 mile oil change.

Adjust according to taste.

I work it out this way, but we get to the same place:

For an auto doing 60mph on land, the typical engine speed is 2,500 rpm. That translates into roughly 12.5 million revs every 5k miles. Most of it is under light load.

For my marine engines, I usually push at 4k rpm, which translates into roughly 6 million revs after 25 hours - just under half compared to the above car.

But that is 2,500 miles at near constant WOT under very heavy load, with carbs. That's enough for a dino HDEO on land or sea.

Le Mans only runs 24 hours.

 

[CMB]

25w-40 Merc oil here. My 351 King Cobra has always run that and doesn't burn a drop. OCI is 50 hours (once a year).

 

[PT1]

Originally Posted By: CMB
25w-40 Merc oil here. My 351 King Cobra has always run that and doesn't burn a drop. OCI is 50 hours (once a year).


Yeah, me too. I stuck with the 25w40. The $10 savings is not worth any issues.

 

[Bror Jace]

"Yeah, me too. I stuck with the 25w40. The $10 savings is not worth any issues."

It's the safe choice ... but OEM oils are rarely excellent and there's probably a better lubricant for this application if one chooses to do the work (searching for places where other brands are sold, using them, sending in for UOAs, etc ...).

Has anyone posted a UOA/VOA of Mercruiser or Volvo oil??

 

[lars11]

UOA would be interesting. I think the volvo 20w50 dino is actually an API SG or SH oil so it is not a recent blend. But, maybe thats what the marine v8 needs?

 

[oilboy123]

Originally Posted By: PT1
Thinking of switching my searay twin 7.4L Horizon engines to a HDEO from Merc 25w40. What do you all think? Which one is best?


I am sure some of the HDEOs that some are mentioning are OK oils but not the best.

Amsoil AME 15w40 Marine HDEO full synthetic is an excellent marine oil. It has military rust additive pack. Good for putting the boat to bed in the fall, or just for all around better rust protection. If the boat is moored it would work well to protect the cylinder walls valves etc from rust.


I feel this oil would be hard to beat.
If you are trying to save money this oil will cost more than a dino HDEO. If you want to save money the AME would not be the best but if you want the best it would be hard to beat.

 

[Michael_in_WA]

Hi all;
Interesting thread. So PT1 did you switch from the Quicksilver 25-40 to the 15-40 HDEO? If so, how did it preform?

So a question, I have a 95 Bayliner with the Mercrusier 350 Thunderbolt. Mercruiser also recommends the Quicksilver 25-40, I would like to change over to 15-40 HDEO also or Napa has a 15-50 synthetic, would this work? Napa said that Valveoline is making their oil. 900 hrs. on the engine and runs strong, don't push the RPM's too much, 3,200 cruise. Any recommendations on a good multi-grade synthetic would be appreciated.

So now for the dumb question from a noobie, what does HDEO stand for?........ Thank you

 

[1OilLover]

Originally Posted By: Michael_in_WA


Hi all;
Interesting thread. So PT1 did you switch from the Quicksilver 25-40 to the 15-40 HDEO? If so, how did it preform?

So a question, I have a 95 Bayliner with the Mercrusier 350 Thunderbolt. Mercruiser also recommends the Quicksilver 25-40, I would like to change over to 15-40 HDEO also or Napa has a 15-50 synthetic, would this work? Napa said that Valveoline is making their oil. 900 hrs. on the engine and runs strong, don't push the RPM's too much, 3,200 cruise. Any recommendations on a good multi-grade synthetic would be appreciated.

So now for the dumb question from a noobie, what does HDEO stand for?........ Thank you


HDEO = Heavy Duty Engine Oil.

I use Mobil 1 15W-50 Synthetic in my 5.7l 300HP Volvo Penta engine and like it. Builds oil pressure quick on start up and holds good pressure at hot idle.

 

[Bror Jace]

Michael_in_WA, Ashland (parent company of Valvoline) has made NAPA oils for years ... but that is not guarantee of quality. As for their 15W-50, I'd like to see some lab testing to see its additive package (add-pack) to see what they are using for anti-wear ... ZDDP? moly? boron? calcium? And how much of each compound.

The odd thing is that 15W-50 is most closely associated with Mobil 1, not Valvoline. Valvoline's heaviest synthetic was labeled 20W-50 last I looked.

The great thing about HDEOs is that they are designed primarily for diesel use and extended drains. To deal with this, they have to have a robust add-pack to deal with fuel dilution and other contaminant issues. It's not a large jump to think these oils would deal well with moisture contamination too ... which is a significant marine issue, of course.

I say go with a 15w40 (Delo, Rotella, Pennzoil Long-Life, etc ...) and watch your gauges. After 25-30 hours, take a sample with a suction pump and send it to a lab like Blackstone for analysis and post the results here for discussion. Cost is only about $25 and is cheap insurance for your pretty boat.

 

[Michael_in_WA]

Thank you for the oil options and advice, I am going to look around town here and see what I can find in 15-40 or 15-50 HDEO synthetic. I have found some Royal Purple 15-40, HDEO, synthetic, might add it is expensive, but no matter if it will stand up to use in a marine engine.

PS.
Bror Jace, it is a pretty boat, teal green on white, very few made in this color combo. Wish I could post picture, again thank you.

 

[PT1]

FWIW Walmart is closing out their Castrol Tection 15w40 HDEO for $7/gallon. I am going to give this a shot this coming fall. After talking with several people many are using HDEO's with no problems.

 

[Mkos1980]

PT1, I saw that also yesterday. They had 4 gallons left and I bought all 4 for the end of this year. Cant go wrong for 7 dollars.