Engine Oil, here we go again

[Merc4ever]

I know this horse was beat to death in past posts but...:deadhorse:

My 2001 Mercruiser owners manual recommends 25-40 Merc oil first, then if not available use 30 or 40 straight weight depending on temp, then goes on to if you can't get Merc or straight use 20-40 and lastly 20-50. At the very end it has synthetic as not recomended?
:clock:

Have they changed there way of thinking since 2001? Or maybe Merc didn't sell synthetic in 2001? Or maybe a damp enviroment :rain: is better with dino oil?

I want to use what is best but the manual says dino, and everyone I know says you can't beat synthetic. :juggle: IDK

 

[IGeeky1]

Re: Engine Oil, here we go again

I found reading through these really helpful in my understanding of oil.

Motor Oil

I use Shell Rotella T6 fwiw, Was using it on my 2001 Jeep Cherokee and figure my 1989 MCM 3.0 should like it too. I hear older engines like the additional zinc and detergents it has in it. At Wally World a gallon is about $22 so not outrageous.

 

[Merc4ever]

Re: Engine Oil, here we go again

I like the thought of using Rotella T6 and it's so easy to get.

 

[oldjeep]

Re: Engine Oil, here we go again

Current recommendations are here:
MerCruiser Fuel & Oil FAQs | Storage & Maintenance MerCruiser FAQs | Mercury Marine

Engine Oil

For optimum engine performance and maximum protection, use the following oil:

Application Recommended Oil
All MerCruiser engines Mercury MerCruiser Full-Synthetic Engine Oil, 20W-40, NMMC FC-W rated

IMPORTANT: Lubrication requirements for catalyzed engines differ from the requirements for non-catalyzed engines. Some marine-grade lubricants contain high levels of phosphorus, which can damage the catalyst system on MerCruiser engines. Although these high-phosphorus lubricants may allow acceptable engine performance, exposure over time will damage the catalyst. Catalysts damaged by lubricants containing high levels of phosphorus may not be covered by the MerCruiser Limited Warranty.

If Mercury MerCruiser Full-Synthetic, 20W-40 oils is unavailable, use the following lubricants, listed in order of recommendation. If you are servicing a catalyst engine, use these for short periods of time only.
1.Mercury/Quicksilver 25W-40 Synthetic Blend, NMMA FC-W-rated 4-cycle MerCruiser oil
2.Mercury/Quicksilver 25W-40, NMMA FC-W-rated 4-cycle MerCruiser oil
3.Other recognized brands of NMMA FC-W-rated 4-cycle oils
4.A good-grade, straight-weight detergent automotive oil according to the last row of the operating chart below.

The only thing they say about things that are not recommended is:
NOTE: We do not recommend 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.

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.

 

[IGeeky1]

Re: Engine Oil, here we go again

hmmm... Rotella T6 does contain a relatively high amount of phosphorus

 

[oldjeep]

Re: Engine Oil, here we go again

hmmm... Rotella T6 does contain a relatively high amount of phosphorus

I highly doubt that your 2001 has a catalytic convertor

 

[IGeeky1]

Re: Engine Oil, here we go again

I highly doubt that your 2001 has a catalytic convertor

I know my 1989 MCM doesn't but had no idea whether or not Merc4ever's boat would or not so thought I'd mention it.

 

[Silvertip]

Re: Engine Oil, here we go again

A 2001 engine is now 12 years old and like cars, TV's, toasters, etc., things have changed. But when it comes to oil, if it says OIL on the can/bottle you can probably use it in your engine (provided that oil is for 4-stroke engines).

 

[Bondo]

Re: Engine Oil, here we go again

A 2001 engine is now 12 years old and like cars, TV's, toasters, etc., things have changed. But when it comes to oil, if it says OIL on the can/bottle you can probably use it in your engine (provided that oil is for 4-stroke engines).

Ayuh,... I completely Agree,....

If you can buy oil in a can or bottle that says "Motor Oil" on it,...
It Ain't gonna hurt yer motor, 1 Bit,...

The motors We run would be perfectly Happy on any "motor oil" sold by WallyWorld,...

Clean oil is what's Really Important,...

 

[Merc4ever]

Re: Engine Oil, here we go again

I know my 1989 MCM doesn't but had no idea whether or not Merc4ever's boat would or not so thought I'd mention it.

Nope. No converter, I think they're stupid because it's just something else to go wrong if I had one I'd remove its guts. I like the Rotela idea I just don't know about oil going down to 5 weight is that too thin? Merc's recomendation starts with at least 20 weight no matter what you read.

That's another thing, Merc recomended no synthetic in my 2001 manual now it's their number one recomendation? :help:

 

[Scott Danforth]

Re: Engine Oil, here we go again

GM sells the motors to VP and Merc. both VP and Merc have different guides. one is 25W40, the other is 10W30.

I buy 15W40 diesel oil for everything I drive. I own mostly flat tappet cams and they like zinc.

 

[Merc4ever]

Re: Engine Oil, here we go again

There's a thing called shear stability and I think it's when you run the oil for a while it drops down to like say for instance: 10 weight. I don't know if that happens in boat motors with this diesel oil or not.

Here is something interesting I just found on Bob the Oil guy forum:

1. The engines work very hard in boats, hours near wot and never ever downhill, and this calls for fairly heavy oils SAE 40 or 50 at temp.
2. The engines are typically also dumping too much fuel during the run cycles (less with electronic controlled injection)
3. They shear oil a lot when running, v6 seem to be the worst.
4. Even with all that water cooling the engine, some oil passages turn very hot so it needs even more visc stability to lube right.

So, what does the makers recommend?
Volvo says 15w50 mineral until like 2004 (Gxi), then 15w50 synthetic. In some cases straight sae30 synthetic is also on the list (Amsoil)
Mercruiser says 25w40.
I think both recommend 50 hrs oci, 100hrs oci on the very newest engines with synthetic.
At 50 hrs the engines have burnt appr. 2000 liters of fuel (at nearly wot...) so it would equal a 1 year oci at 20000km on a medium car.

I think that the risk for fuel dilution and shearing making the oil thinner is why stout oils with less VI improvers are preferred. Then there is seldom a need for better cold starting either so a 5w-X is not on the list even if your 5w40 would probably do just fine at least when fresh and strong...

I run a volvo 5.0Gi on Mobil Delvac MX 15W-40 and oci of 40-50 hrs and see stable pressure all season.

Seriously, buy rotella, delvac etc. 15w40 or merc 25w40, change often and be happy. If you get a deal buying bigger packs of merc 25w40 get that instead. There is not much to gain from synthetic and low visc oils in a marine v8.

And for the wise comments:
- They are all car engines and will do well on cheap 10-30. Nope, unless you are oozing it along in a canoe which is like truck use.
- The diesels are worse on oil so the simple lo saps lo protection stuff will do as well. Nope, diesels are not necessarily worse on oil, but they are different.
- You need to use the manufacturer oil. Nope, not for the engines. But some duoprop outdrives are picky on oil. Beware.

 

[Merc4ever]

Re: Engine Oil, here we go again

You know guys, after some research I'm thinking that the Merc or Sierra 25w-40 synthetic blend is the best to use if you have the non-catalytic pre 2009 engine. Otherwise you should use full synthetic as to not to clog your exhaust.

It's not too thin and you can get the synthetic effect but still have the protection of some zinc.
...plus it don't cost you an arm and a leg! :greedy_dollars:

 

[oldjeep]

Re: Engine Oil, here we go again

You know guys, after some research I'm thinking that the Merc or Sierra 25w-40 synthetic blend is the best to use if you have the non-catalytic pre 2009 engine. Otherwise you should use full synthetic as to not to clog your exhaust.

It's not too thin and you can get the synthetic effect but still have the protection of some zinc.
...plus it don't cost you an arm and a leg! :greedy_dollars:

Guess I don't worry too much about the oil cost. $30 for a 1 gallon jug of merc synthetic each year isn't much of a drop in the bucket of the yearly boat costs

 

[agallant80]

Re: Engine Oil, here we go again

I posted a question once asking if anyone who works on these things for a living has even seen an engine fail due to oil. Guess what? Not one person could say that they have.

 

[oldjeep]

Re: Engine Oil, here we go again

I posted a question once asking if anyone who works on these things for a living has even seen an engine fail due to oil. Guess what? Not one person could say that they have.

You would be hard pressed to attribute any failure to oil specifically. Failures from oil are just increased wear over the years until something finally wears out.

 

[HT32BSX115]

Re: Engine Oil, here we go again

You would be hard pressed to attribute any failure to oil specifically. Failures from oil are just increased wear over the years until something finally wears out.

AND, marine engines don't usually wear out. They usually "die" from freeze damage or a complete lack of ANY maintenance!!

 

[Bondo]

Re: Engine Oil, here we go again

Ayuh,.... I've changed a few motors that died from a Lack of oil,....

But never because of the Wrong oil,...

 

[Merc4ever]

Re: Engine Oil, here we go again

Guess I don't worry too much about the oil cost. $30 for a 1 gallon jug of merc synthetic each year isn't much of a drop in the bucket of the yearly boat costs

But are you missing out on Zinc protection? Racing car owners love using it and the synthetic Merc doesn't have it.

Valvoline says:
"The anti-wear additive simply referred to as zinc by most car enthusiasts is actually short for Zinc DialkylDithiophosphates or ZDDP. Its primary role is to prevent metal-to-metal contact between engine parts by forming a protective film. Despite being referred to as zinc, this additive actually contains zinc and phosphorus, with phosphorus performing the anti-wear function in the motor oil with zinc"

IDK, maybe the goodness of synthetic out weighs the goodness of Zinc?

 

[oldjeep]

Re: Engine Oil, here we go again

But are you missing out on Zinc protection? Racing car owners love using it and the synthetic Merc doesn't have it.

Valvoline says:
"The anti-wear additive simply referred to as zinc by most car enthusiasts is actually short for Zinc DialkylDithiophosphates or ZDDP. Its primary role is to prevent metal-to-metal contact between engine parts by forming a protective film. Despite being referred to as zinc, this additive actually contains zinc and phosphorus, with phosphorus performing the anti-wear function in the motor oil with zinc"

IDK, maybe the goodness of synthetic out weighs the goodness of Zinc?

Whatever the mfg says works is fine with me. If they say that bulk dino oil is fine like my Ram does, then I use that. If they say a corvette needs Mobile 1, then that is what it gets.

If Merc though they needed diesel oil in their engines then they would probably spec it that way.

So I guess what I'm saying is that I don't have a preference for anything in particular (won't be shaving my head and joining the cult of Amsoil any time soon). Everything gets what the book says and if there is a 1st choice and it is available then that is what I use.