Synthetic oil

hack4alivin

Active Member
TECHNICAL Contributor
Apr 18, 2008
2,518
Joppa, Maryland
Boat Info
320 Dancer
Engines
Twin 350 V Drives
I have used synthetic oil in my new cars for years, changing over on the first oil change. Now I am considering using Mercury’s Synthetic Blend oil for my next oil change on the boat. The engines now have a little over 200 hours on them. Would this be a problem? Any thoughts…
 
I have contemplated this too........Looking forward to the responses.
Merc offers a Full Synthetic versus a synthetic blend too don't they?
 
High performance engines are generally broken in at the factory.

Yes. Use Merc Synthetic Blend. Merc claims that it is approved for all of their engines, and recommended. I don't know of any pure synthetic oil by Merc, but that doesn't mean that it doesn't exist.
 
I run it in all my boats. I even run it in my mud motor (for duck hunting). It is the best thing you will ever do for your boat. You should run it in your vehicles too. It comes standard I think in most cars, I know my Lexus does but I switched over my Ford truck and I couldn't believe the improved noise reduction. :thumbsup:
 
If and only if you change your oil regularly, dino oil that meets your manufacturer's recommendation is sufficient.

Doug
 
On a related note I did a project 9+ years ago for an oil additive company. I got the tour of the plant, saw where they ran the engines for hours and hours, broke all the engines down for testing, etc. At the end of the tour I asked them if all these additives really matter. The guy leaned over, and whispered in my ear "No, not if you change you oil regularly, but don't tell anyone, it's how we make a living".
 
The first 500 hours of a gas engines life will dictate if it will see 1000, 1500 or 2000 hours. Are synthetic oils better? Sure they are.

The car companies know this for a fact. My 1992 Corvette required it from the factory because they did away with the oil cooler that year. It has 175K miles on the engine and runs great.

Conditions in boats are much more severe than cars and a reasonable deduction is that anything that manages friction better is a good thing. In the costs of boat ownership, gas engine oil changes are not that expensive, so buying high quality oil and filters just seems to make sense.

I switched mine to synthetic at 300 hours and have close to 800 hours on them today. The new generator also has synthetic in it.

-John
 
The main advantages of synthetic are...

Better flow at cold temperature.
Better oxidative stbility at high temperature.
Fewer viscosity modifiers for the same range.
Pure base.

When you start a cold engine, it's hard to get the oil everywhere it needs to be. If you live in the north, you know how long it takes your car to sound right. Sythentic will get there much quicker.

Penzoil used to advertise that they had the most pure base at 97%. That means that 3% is garbage, most likely suspended carbon, which cokes at high temperature and becomes abrasive. You also have to add a bunch of long molecule modifiers to get the desired viscosity range... how long do you think they live?

In a high tolerance engine, break-in is quick and you can use synthetic almost immediately. In old sluged-up engines, synthetic used to have very high detergent properties, and there were stories about it breaking sludge loose that would clog a passage way and starve an area... or the sludge may have coated over a gasket, that then dried out and when removed by the synthetic, would now leak oil.

High performance cars run hot and hard, it's good stuff. Cold weather climate, good stuff. But most boats have great cooling, overall run cool, are babied until warmed up and aren't started at -25F. I don't use it in the boat although all my cars and trucks do.
 
"I switched mine to synthetic at 300 hours"

What brand and weight? I assume you are running big block carburated 454s too.

We have about 170 on our Jasper remans and I have thought about converting. I currently use QuickSilver 25-40 blend, recommended by Jasper:

"Premium SAE 25W-40 blended with special high grade oils and formulated without viscosity improvers, giving a premium quality multiviscosity 4-cycle motor oil. Suitable for use in gasoline or diesel sterndrive and inboard engines. Meets API service SJ, CF-2, CH-4."
 
How about the genny? Straight 30W Mobil 1, or what? I would really like to extend the life of the genny as well (I use the Merc synth in the 8.1's).
 
I run the Merc blend in my boat just for warranty purposes, if something should happen I am running what they say. I really don't know that I will change when warranty runs out. My old boat ran on Kendall GT1 20-50 for all of the 17 years that I had it, I ran the same stuff in all of my vehicles, ran one over 300,000 the other two have over 200,000 miles. I had to change oil, can not get the Kendall in my area anymore, I now run Castrol High Mileage oil. I wonder what Bob the oil guy would have to say about this topic. :grin:
 
This is the stuff I use in my Cummins:

http://www.valvoline.com/pages/products/product_detail.asp?product=103

Cummins has some deal with Valvoline on the testing or development or something with that oil... It's synthetic.

I've been using synthetics in my cars since the mid-80's. Not sure it really makes a difference but I've always got high milage on them without burning oil. My current car came with Mobil 1 from the factory and it gets changed every 10,000 miles which I guess saves a little on the oil change front.
 
This is the stuff I use in my Cummins:

http://www.valvoline.com/pages/products/product_detail.asp?product=103

Cummins has some deal with Valvoline on the testing or development or something with that oil... It's synthetic.

I've been using synthetics in my cars since the mid-80's. Not sure it really makes a difference but I've always got high milage on them without burning oil. My current car came with Mobil 1 from the factory and it gets changed every 10,000 miles which
I guess saves a little on the oil change front.

I agree it has been great for our cars. My wife’s BMW comes standard with it and the recommend oil changes are around 10k as well. (At $300 per oil change).

I want to start doing the oil changes myself in the boat so knowing the advantages of it in the car; it would seem to be best in the boat as well.
 
How about the genny? Straight 30W Mobil 1, or what? I would really like to extend the life of the genny as well (I use the Merc synth in the 8.1's).

I changed my genny oil @ 20hrs to synthetic Mobil 1 0W-40, per the manual and our climate here.

Merc also recommends their synthetic for the Horizon 8.1L, but haven't reached the engine hrs yet.

BTW my Porsche engine comes with synthetic Mobil 1 and recommends oil changes at 20K miles with synthetic Mobil 1 0W-40!! This is the famous "bullet proof" GT1 split block inverted 6 engine (the actual engine you see racing at LeMans and Sebring). I don't follow Porsche's recommendation here and change the oil & filters (8.5 qts with 2 oil filters) once a year, but this is a certainly a testamony for synthetic Mobil 1 oils, 20K miles on a high performance engine! My older 911 C2 air cooled engine also uses synthetic Mobil 1 per Porsche's recommendation changed @ 7.5K miles.

So I agree with others that with all the higher performance engines running synthetics our marine engines will benefit as well and Merc at least for the Horizons is following this. Would be interesting to see what Volvo and others are doing??

Mike
 
Why not check with Mercruiser?
http://www.mercurymarine.com/serviceandwarranty/mercruiserfaqs/fueloil.php

What type of oil should I use? Can I use synthetic oil?
Engine Oil
To help obtain optimum engine performance and to provide maximum protection, we strongly recommend the use of the following oils listed in the order of recommendation:
  1. MerCruiser / Quicksilver Synthetic Blend, NMMA FC-W rated, 4 cycle oil.
  2. MerCruiser / Quicksilver 25W40 NMMA FC-W rated oil.
  3. A NMMA FC-W rated oil.
  4. MerCruiser / Quicksilver 4-cycle 25W40, non FC-W rated oil.
  5. A good grade straight weight detergent automotive oil per the operating chart below.
NOTE: The use of non-detergent oils, multi-viscosity oils (other than as specified), non-FC-W rated synthetic oils, low quality oils or oils that contain solid additives are specifically not recommended.

faqs_temp.gif


This crankcase oil recommendation supersedes all previously printed crankcase oil recommendations for MerCruiser gasoline engines. The reason for this change is to include the newer engine oils that are now available in the recommendation.
Older owner manuals, service manuals and other publications that are not regularly updated will not be revised to show this latest engine oil recommendation. Current owners manuals, service manuals and other service publications that receive regular updates will receive this revised recommendation the next time they are updated.


BTW
I run mineral oil in everything and change it every 3,000 miles. I typically run a car 200,000 miles or so. Usually the body, or something, gives out before the engine. Never had an engine failure. Only engine I had to open was an old Mopar 318 that had an exhaust valve recession problem, which is not oil related. My Navigator is pushing 300,000 miles and only has 5W-30 mineral oil. The only exception is my wife's car. I'm trying synthetic in her Vanden Plas.

Best regards,
Frank
 
Last edited:
So the question nobody asked....or answered.

How often do you change the oil in your boats with synthetic? Do you go longer between changes than with Dino?
 
I have never used synthetics in any of my vehicles. I had 160,000 on an 11 year old Honda Accord and still going strong when sold. I currently have 75,000 miles on a Toyota Tundra and no oil related problems. The recommended interval for the Tundra is 7,500 miles. I tend to change at multiples of 5,000 since I can remember multiples of 5 not because I think it needs changing more often. Certainly these are not high performance engines but the engine in my cobalt is the same one that is used in the Ford Mustang at some point.

I saw an interesting article in consumer reports where they had engines in taxi cabs with oil changes at different intervals and different types. Then at 100,000 miles tore apart the engines and took calipers to typically worn parts. They found no measurable difference even when extending oil changes out to 12,000 miles I believe. They did not test synthetics because they did not have enough cars. (I read this years ago.)

I once sat next to a guy on a plane who did work for some of the big nuclear and hydro electric plants. His job was to test oil samples from some of the plant equipment to determine when to change it. These machines were using a lot of oil so time to change was determined from bench testing no a specified interval.

In the cobalt 5.0 volvo I have always used straight 30 weight dino oil with no problems. Interesting that the 7.4 mercruiser recommends a multiviscosity oil.

John
 
For my boat, I'm going with synthetic blend every year or 75 hours, whichever comes first.
 
I have used synthetics in my vehicles and it seems to prolong the engine life considerably. Been think about going to amsoil (SAE 10W-40 Formula 4-Stroke® Marine Synthetic Motor Oil) it qualifies under mercs guide lines.:thumbsup:
 
Next time you are in front of your/a mechanic, ask the question I always ask: "Tell me about a case where you saw an engine fail because of oil, whether that be not changed frequently enough or using the wrong kind of oil". The answer I receive 100% of the time is "I can't".
 

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