Engine Oil for Older Mercs

[AKBASSKING]

What do you think? Would you switch to 25W-40 or stay with straight 30W?:huh:

Here is the question I sent MerCruiser:

Serial Number: 0A514643
Model Number: 3263364
Dealer Name:
Boat Manufacturer: Sea Ray
Boat Model: 1986 300DB

Contact By: E-Mail

Comments:
This is a 1986 model year boat. The MerCruiser manual states the engine oil should be straight 30w oil. I understand MerCruiser is now recommending something different?

What oil is now recommended for these old but still working engines? They are the 260hp model.


Mercury Marine
Outboard_Customer_Assistance@mercmarine.com
http://www.mercurymarine.com



Here was their response:

Mr. Teseniar,

Normally MerCruiser would recommend that you use a MerCruiser Oil 25 W 40 in our engines.

On our product that has been in service for 24+ years we would recommend that you continue to use the same oil that the previous owner has been using.

A good grade of straight 30 weight oil will not hurt the engine and has been helping to keep it running for several years. MerCruiser has no data on switching from one weight of oil to another weight of oil after this many years and cannot tell you if there will be any unforeseen problems.

If you would like to speak with a MerCruiser Consumer Service Representative please feel free to contact us at 405-743-6566.


Best regards,

Jo-Ann Lawson
Consumer Service Specialist
MerCruiser Customer Service

 

[northern]

I use SAE 40 and it seems to work fine. The manual said to use it for the water temperature we are in. The only problem I have with it is it takes a long time to drain. We have 1750 hrs on each engine an they use 1/2 quart per 100 hours. I do not intend to change.

 

[carterchapman]

I'm with you Northern - I wouldn't change either. 1750 hours - terrific.

I've said this before - we can argue oil like we argue Ford vs. GM (remember - never pick a fight with a man who owns a Chrysler product, because he's mad already!). We pilots love to argue Boeing vs. Airbus.

On older cars and trucks that I've owned, I ran straight 40 wt - especially living in CA, South TX, and FL with rare temps below 32°F. Never had a problem, and got 200K+ miles out of GM auto 454's and 350's.

Seems like the US auto manufacturers "tightened" their tolerances in the mid to late 90's, and now engines run fine on 5W20, don't use any oil in 6K oil changes (vs. the older 3K recommendation), and get better mileage to boot. My colleague's bimmer goes 22K between changes on his oil computer readout - and he now has 255K miles on it. Can't argue with that.

So, what do I use on my '05 340 with 8.1's? Full synthetic 20W40 - Mercruiser's latest recommendation. Would I be comfortable using their synthetic blend or regular 25W40? Yes I would, but I choose to use full synthetic - just like I use in my Northstar XLR and Allante. What do I use in our GM SUVs? 5W30 conventional oil.

Now, get into diesels and there are some very specific oil recommendations that vary by model. As Frank W. has stated, a lot of problems can be caused by using multi viscosity oil in certain diesel engines. Certain additives can cause problems as well.

I think Mercruiser gave great advice in a previous post - if it's been working for 24 years, don't change the type of oil.

"And that's all I have to say about that"...

 

[my3sons]

What do you think? Would you switch to 25W-40 or stay with straight 30W?:huh:

I personally would not switch.
Early in my career, a well respected individual in the petroleum field told me that the best oil to run in a particular application is the one the manufacturer of the motor recommended on the day the motor was built.

Sounds to me as though you guys have gotten along nicely doing exactly that.

 

[Dick Whetstone]

I am the second owner of an immaculate 1966 (yes it is 45 years old) 17 foot Glassmaster powered by a 110 HP Mercruiser. This Mercruiser is so old that it is painted white, not black. It is anybody's guess how many hours are on it. When it was new the first owner took it on a trip from Charleston, SC to Miami, FL.

It has always used straight 30 wt Havoline. After 45 years it still runs great and it uses no oil. I change oil every year and I don't plan to change things at this late date.

 

[2000SEARAY280SS]

stick with what works

same old same old

 

[CV-23]

I'm using Delo 15w40 in my 454 this year...changed it in the fall of 2010. I'm going to watch cold and warm oil pressures and see how it works. Previous records I found was straight 30W was run in my 454 in the past. I've always used merCruiser 25w40 in my 5.7L and Yamaha 850 Special motorcycle. Good oil but $8 a quart is a bit of a stretch for oil that I don't get 50hrs a year on, Mike.

 

[1956olds]

I use delo 400 40w it was recomended by a previous mechanic at brennans who is retired into west marine store.

 

[Nassau Weekender]

Same here Delo 400 straight 40w.

Its the most suitable oil I stock - so I get it at a good price.

Even though it may be a stright weight oil, it is not the same Delo 400 straight 40 it was 10 years ago. So you are still putting a modern product in your engines.

The only thing that is probably worse for our engines than it was 10 years ago are the fuels we must use.

 

[ChrisJA]

I have a 1987 Searay 300DB Sedan Bridge with Twin 260 Mercruiser V Drives. I dock the boat at a Marina in Highlands NJ and would like to know what would be the best oil to use in these engines? I am not sure what oil has been used in the past. There is 375 hours on each engine and so far I do not have any problems.

In this forum the advise ranged for use 30W to 25 W 40 what is best.

Regards

ChrisJA

 

[BillK2632]

My old Correct Craft Ski Tique had a Commander 302 (Ford block), recommended oil at the time was a straight 40wt. We used Valvoline 40wt and put @2500hrs on that engine - I few maintenance items (things wear out eventually) but it was still running great when we sold it. No oil leaks, did not use and oil. I would not change oil type - stick with what has worked for 24 years. Now, on my newer boats, I have been using the recommended Mercruiser 25w40 synthetic blend, but my manual states I can use a straight 30 or 40wt if the 25w40 is not available.